diff --git a/client/src/actions/entry/user.js b/client/src/actions/entry/user.js
index 8d157958..32cf63cd 100755
--- a/client/src/actions/entry/user.js
+++ b/client/src/actions/entry/user.js
@@ -51,6 +51,18 @@ export const clearCurrentUserPasswordUpdateError = () => ({
   payload: {},
 });
 
+export const updateCurrentUserUsername = (data) => ({
+  type: EntryActionTypes.CURRENT_USER_USERNAME_UPDATE,
+  payload: {
+    data,
+  },
+});
+
+export const clearCurrentUserUsernameUpdateError = () => ({
+  type: EntryActionTypes.CURRENT_USER_USERNAME_UPDATE_ERROR_CLEAR,
+  payload: {},
+});
+
 export const uploadCurrentUserAvatar = (file) => ({
   type: EntryActionTypes.CURRENT_USER_AVATAR_UPLOAD,
   payload: {
diff --git a/client/src/actions/user.js b/client/src/actions/user.js
index c00ccb27..5464795c 100644
--- a/client/src/actions/user.js
+++ b/client/src/actions/user.js
@@ -36,6 +36,13 @@ export const clearUserPasswordUpdateError = (id) => ({
   },
 });
 
+export const clearUserUsernameUpdateError = (id) => ({
+  type: ActionTypes.USER_USERNAME_UPDATE_ERROR_CLEAR,
+  payload: {
+    id,
+  },
+});
+
 export const deleteUser = (id) => ({
   type: ActionTypes.USER_DELETE,
   payload: {
@@ -202,6 +209,30 @@ export const updateUserPasswordFailed = (id, error) => ({
   },
 });
 
+export const updateUserUsernameRequested = (id, data) => ({
+  type: ActionTypes.USER_USERNAME_UPDATE_REQUESTED,
+  payload: {
+    id,
+    data,
+  },
+});
+
+export const updateUserUsernameSucceeded = (id, username) => ({
+  type: ActionTypes.USER_USERNAME_UPDATE_SUCCEEDED,
+  payload: {
+    id,
+    username,
+  },
+});
+
+export const updateUserUsernameFailed = (id, error) => ({
+  type: ActionTypes.USER_USERNAME_UPDATE_FAILED,
+  payload: {
+    id,
+    error,
+  },
+});
+
 export const uploadUserAvatarRequested = (id) => ({
   type: ActionTypes.USER_AVATAR_UPLOAD_REQUESTED,
   payload: {
diff --git a/client/src/api/users.js b/client/src/api/users.js
index 4851a004..2c28c976 100755
--- a/client/src/api/users.js
+++ b/client/src/api/users.js
@@ -16,6 +16,9 @@ const updateUserEmail = (id, data, headers) => socket.patch(`/users/${id}/email`
 const updateUserPassword = (id, data, headers) =>
   socket.patch(`/users/${id}/password`, data, headers);
 
+const updateUserUsername = (id, data, headers) =>
+  socket.patch(`/users/${id}/username`, data, headers);
+
 const uploadUserAvatar = (id, file, headers) =>
   http.post(
     `/users/${id}/upload-avatar`,
@@ -34,6 +37,7 @@ export default {
   updateUser,
   updateUserEmail,
   updateUserPassword,
+  updateUserUsername,
   uploadUserAvatar,
   deleteUser,
 };
diff --git a/client/src/components/AddUserPopup/AddUserPopup.jsx b/client/src/components/AddUserPopup/AddUserPopup.jsx
index c6b202ca..2c3dc7f5 100755
--- a/client/src/components/AddUserPopup/AddUserPopup.jsx
+++ b/client/src/components/AddUserPopup/AddUserPopup.jsx
@@ -8,6 +8,7 @@ import { withPopup } from '../../lib/popup';
 import { Input, Popup } from '../../lib/custom-ui';
 
 import { useForm } from '../../hooks';
+import { isUsername } from '../../utils/validator';
 
 import styles from './AddUserPopup.module.css';
 
@@ -16,17 +17,23 @@ const createMessage = (error) => {
     return error;
   }
 
-  if (error.message === 'User is already exist') {
-    return {
-      type: 'error',
-      content: 'common.userIsAlreadyExist',
-    };
+  switch (error.message) {
+    case 'Email already in use':
+      return {
+        type: 'error',
+        content: 'common.emailAlreadyInUse',
+      };
+    case 'Username already in use':
+      return {
+        type: 'error',
+        content: 'common.usernameAlreadyInUse',
+      };
+    default:
+      return {
+        type: 'warning',
+        content: 'common.unknownError',
+      };
   }
-
-  return {
-    type: 'warning',
-    content: 'common.unknownError',
-  };
 };
 
 const AddUserPopup = React.memo(
@@ -38,6 +45,7 @@ const AddUserPopup = React.memo(
       email: '',
       password: '',
       name: '',
+      username: '',
       ...defaultData,
     }));
 
@@ -46,12 +54,14 @@ const AddUserPopup = React.memo(
     const emailField = useRef(null);
     const passwordField = useRef(null);
     const nameField = useRef(null);
+    const usernameField = useRef(null);
 
     const handleSubmit = useCallback(() => {
       const cleanData = {
         ...data,
         email: data.email.trim(),
         name: data.name.trim(),
+        username: data.username.trim() || null,
       };
 
       if (!isEmail(cleanData.email)) {
@@ -69,6 +79,11 @@ const AddUserPopup = React.memo(
         return;
       }
 
+      if (cleanData.username && !isUsername(cleanData.username)) {
+        usernameField.current.select();
+        return;
+      }
+
       onCreate(cleanData);
     }, [onCreate, data]);
 
@@ -78,10 +93,20 @@ const AddUserPopup = React.memo(
 
     useEffect(() => {
       if (wasSubmitting && !isSubmitting) {
-        if (!error) {
+        if (error) {
+          switch (error.message) {
+            case 'Email already in use':
+              emailField.current.select();
+
+              break;
+            case 'Username already in use':
+              usernameField.current.select();
+
+              break;
+            default:
+          }
+        } else {
           onClose();
-        } else if (error.message === 'User is already exist') {
-          emailField.current.select();
         }
       }
     }, [isSubmitting, wasSubmitting, error, onClose]);
@@ -136,6 +161,22 @@ const AddUserPopup = React.memo(
               className={styles.field}
               onChange={handleFieldChange}
             />
+            <div className={styles.text}>
+              {t('common.username')} (
+              {t('common.optional', {
+                context: 'inline',
+              })}
+              )
+            </div>
+            <Input
+              fluid
+              ref={usernameField}
+              name="username"
+              value={data.username}
+              readOnly={isSubmitting}
+              className={styles.field}
+              onChange={handleFieldChange}
+            />
             <Button
               positive
               content={t('action.addUser')}
diff --git a/client/src/components/Header/Header.jsx b/client/src/components/Header/Header.jsx
index 41c05311..7f18bcb6 100755
--- a/client/src/components/Header/Header.jsx
+++ b/client/src/components/Header/Header.jsx
@@ -18,6 +18,8 @@ const Header = React.memo(
     onNotificationDelete,
     onUserUpdate,
     onUserAvatarUpload,
+    onUserUsernameUpdate,
+    onUserUsernameUpdateMessageDismiss,
     onUserEmailUpdate,
     onUserEmailUpdateMessageDismiss,
     onUserPasswordUpdate,
@@ -46,12 +48,16 @@ const Header = React.memo(
           <UserPopup
             email={user.email}
             name={user.name}
+            username={user.username}
             avatar={user.avatar}
             isAvatarUploading={user.isAvatarUploading}
+            usernameUpdateForm={user.usernameUpdateForm}
             emailUpdateForm={user.emailUpdateForm}
             passwordUpdateForm={user.passwordUpdateForm}
             onUpdate={onUserUpdate}
             onAvatarUpload={onUserAvatarUpload}
+            onUsernameUpdate={onUserUsernameUpdate}
+            onUsernameUpdateMessageDismiss={onUserUsernameUpdateMessageDismiss}
             onEmailUpdate={onUserEmailUpdate}
             onEmailUpdateMessageDismiss={onUserEmailUpdateMessageDismiss}
             onPasswordUpdate={onUserPasswordUpdate}
@@ -76,6 +82,8 @@ Header.propTypes = {
   onNotificationDelete: PropTypes.func.isRequired,
   onUserUpdate: PropTypes.func.isRequired,
   onUserAvatarUpload: PropTypes.func.isRequired,
+  onUserUsernameUpdate: PropTypes.func.isRequired,
+  onUserUsernameUpdateMessageDismiss: PropTypes.func.isRequired,
   onUserEmailUpdate: PropTypes.func.isRequired,
   onUserEmailUpdateMessageDismiss: PropTypes.func.isRequired,
   onUserPasswordUpdate: PropTypes.func.isRequired,
diff --git a/client/src/components/Login/Login.jsx b/client/src/components/Login/Login.jsx
index e0e1a967..bd787afa 100755
--- a/client/src/components/Login/Login.jsx
+++ b/client/src/components/Login/Login.jsx
@@ -8,6 +8,7 @@ import { useDidUpdate, usePrevious, useToggle } from '../../lib/hooks';
 import { Input } from '../../lib/custom-ui';
 
 import { useForm } from '../../hooks';
+import { isUsername } from '../../utils/validator';
 
 import styles from './Login.module.css';
 
@@ -17,12 +18,12 @@ const createMessage = (error) => {
   }
 
   switch (error.message) {
-    case 'Email does not exist':
+    case 'Invalid email or username':
       return {
         type: 'error',
-        content: 'common.emailDoesNotExist',
+        content: 'common.invalidEmailOrUsername',
       };
-    case 'Password is not valid':
+    case 'Invalid password':
       return {
         type: 'error',
         content: 'common.invalidPassword',
@@ -51,7 +52,7 @@ const Login = React.memo(
     const wasSubmitting = usePrevious(isSubmitting);
 
     const [data, handleFieldChange, setData] = useForm(() => ({
-      email: '',
+      emailOrUsername: '',
       password: '',
       ...defaultData,
     }));
@@ -59,17 +60,17 @@ const Login = React.memo(
     const message = useMemo(() => createMessage(error), [error]);
     const [focusPasswordFieldState, focusPasswordField] = useToggle();
 
-    const emailField = useRef(null);
+    const emailOrUsernameField = useRef(null);
     const passwordField = useRef(null);
 
     const handleSubmit = useCallback(() => {
       const cleanData = {
         ...data,
-        email: data.email.trim(),
+        emailOrUsername: data.emailOrUsername.trim(),
       };
 
-      if (!isEmail(cleanData.email)) {
-        emailField.current.select();
+      if (!isEmail(cleanData.emailOrUsername) && !isUsername(cleanData.emailOrUsername)) {
+        emailOrUsernameField.current.select();
         return;
       }
 
@@ -82,17 +83,17 @@ const Login = React.memo(
     }, [onAuthenticate, data]);
 
     useEffect(() => {
-      emailField.current.select();
+      emailOrUsernameField.current.select();
     }, []);
 
     useEffect(() => {
       if (wasSubmitting && !isSubmitting && error) {
         switch (error.message) {
-          case 'Email does not exist':
-            emailField.current.select();
+          case 'Invalid email or username':
+            emailOrUsernameField.current.select();
 
             break;
-          case 'Password is not valid':
+          case 'Invalid password':
             setData((prevData) => ({
               ...prevData,
               password: '',
@@ -136,12 +137,12 @@ const Login = React.memo(
                     )}
                     <Form size="large" onSubmit={handleSubmit}>
                       <div className={styles.inputWrapper}>
-                        <div className={styles.inputLabel}>{t('common.email')}</div>
+                        <div className={styles.inputLabel}>{t('common.emailOrUsername')}</div>
                         <Input
                           fluid
-                          ref={emailField}
-                          name="email"
-                          value={data.email}
+                          ref={emailOrUsernameField}
+                          name="emailOrUsername"
+                          value={data.emailOrUsername}
                           readOnly={isSubmitting}
                           className={styles.input}
                           onChange={handleFieldChange}
diff --git a/client/src/components/UserPopup/EditEmailStep.jsx b/client/src/components/UserPopup/EditEmailStep.jsx
index 8dc26c1f..d15bbe60 100644
--- a/client/src/components/UserPopup/EditEmailStep.jsx
+++ b/client/src/components/UserPopup/EditEmailStep.jsx
@@ -16,12 +16,12 @@ const createMessage = (error) => {
   }
 
   switch (error.message) {
-    case 'User is already exist':
+    case 'Email already in use':
       return {
         type: 'error',
-        content: 'common.userIsAlreadyExist',
+        content: 'common.emailAlreadyInUse',
       };
-    case 'Current password is not valid':
+    case 'Invalid current password':
       return {
         type: 'error',
         content: 'common.invalidCurrentPassword',
@@ -83,11 +83,11 @@ const EditEmailStep = React.memo(
       if (wasSubmitting && !isSubmitting) {
         if (error) {
           switch (error.message) {
-            case 'User is already exist':
+            case 'Email already in use':
               emailField.current.select();
 
               break;
-            case 'Current password is not valid':
+            case 'Invalid current password':
               setData((prevData) => ({
                 ...prevData,
                 currentPassword: '',
diff --git a/client/src/components/UserPopup/EditPasswordStep.jsx b/client/src/components/UserPopup/EditPasswordStep.jsx
index 50f46cb6..ea1d622a 100644
--- a/client/src/components/UserPopup/EditPasswordStep.jsx
+++ b/client/src/components/UserPopup/EditPasswordStep.jsx
@@ -15,7 +15,7 @@ const createMessage = (error) => {
   }
 
   switch (error.message) {
-    case 'Current password is not valid':
+    case 'Invalid current password':
       return {
         type: 'error',
         content: 'common.invalidCurrentPassword',
@@ -67,7 +67,7 @@ const EditPasswordStep = React.memo(
       if (wasSubmitting && !isSubmitting) {
         if (!error) {
           onClose();
-        } else if (error.message === 'Current password is not valid') {
+        } else if (error.message === 'Invalid current password') {
           setData((prevData) => ({
             ...prevData,
             currentPassword: '',
diff --git a/client/src/components/UserPopup/EditUsernameStep.jsx b/client/src/components/UserPopup/EditUsernameStep.jsx
new file mode 100644
index 00000000..00c8709f
--- /dev/null
+++ b/client/src/components/UserPopup/EditUsernameStep.jsx
@@ -0,0 +1,182 @@
+import React, { useCallback, useEffect, useMemo, useRef } from 'react';
+import PropTypes from 'prop-types';
+import { useTranslation } from 'react-i18next';
+import { Button, Form, Message } from 'semantic-ui-react';
+import { useDidUpdate, usePrevious, useToggle } from '../../lib/hooks';
+import { Input, Popup } from '../../lib/custom-ui';
+
+import { useForm } from '../../hooks';
+import { isUsername } from '../../utils/validator';
+
+import styles from './EditUsernameStep.module.css';
+
+const createMessage = (error) => {
+  if (!error) {
+    return error;
+  }
+
+  switch (error.message) {
+    case 'Username already in use':
+      return {
+        type: 'error',
+        content: 'common.usernameAlreadyInUse',
+      };
+    case 'Invalid current password':
+      return {
+        type: 'error',
+        content: 'common.invalidCurrentPassword',
+      };
+    default:
+      return {
+        type: 'warning',
+        content: 'common.unknownError',
+      };
+  }
+};
+
+const EditUsernameStep = React.memo(
+  ({ defaultData, username, isSubmitting, error, onUpdate, onMessageDismiss, onBack, onClose }) => {
+    const [t] = useTranslation();
+    const wasSubmitting = usePrevious(isSubmitting);
+
+    const [data, handleFieldChange, setData] = useForm({
+      username: '',
+      currentPassword: '',
+      ...defaultData,
+    });
+
+    const message = useMemo(() => createMessage(error), [error]);
+    const [focusCurrentPasswordFieldState, focusCurrentPasswordField] = useToggle();
+
+    const usernameField = useRef(null);
+    const currentPasswordField = useRef(null);
+
+    const handleSubmit = useCallback(() => {
+      const cleanData = {
+        ...data,
+        username: data.username.trim() || null,
+      };
+
+      if (cleanData.username && !isUsername(cleanData.username)) {
+        usernameField.current.select();
+        return;
+      }
+
+      if (cleanData.username === username) {
+        onClose();
+        return;
+      }
+
+      if (!cleanData.currentPassword) {
+        currentPasswordField.current.focus();
+        return;
+      }
+
+      onUpdate(cleanData);
+    }, [username, onUpdate, onClose, data]);
+
+    useEffect(() => {
+      usernameField.current.select();
+    }, []);
+
+    useEffect(() => {
+      if (wasSubmitting && !isSubmitting) {
+        if (error) {
+          switch (error.message) {
+            case 'Username already in use':
+              usernameField.current.select();
+
+              break;
+            case 'Invalid current password':
+              setData((prevData) => ({
+                ...prevData,
+                currentPassword: '',
+              }));
+              focusCurrentPasswordField();
+
+              break;
+            default:
+          }
+        } else {
+          onClose();
+        }
+      }
+    }, [isSubmitting, wasSubmitting, error, onClose, setData, focusCurrentPasswordField]);
+
+    useDidUpdate(() => {
+      currentPasswordField.current.focus();
+    }, [focusCurrentPasswordFieldState]);
+
+    return (
+      <>
+        <Popup.Header onBack={onBack}>
+          {t('common.editUsername', {
+            context: 'title',
+          })}
+        </Popup.Header>
+        <Popup.Content>
+          {message && (
+            <Message
+              // eslint-disable-next-line react/jsx-props-no-spreading
+              {...{
+                [message.type]: true,
+              }}
+              visible
+              content={t(message.content)}
+              onDismiss={onMessageDismiss}
+            />
+          )}
+          <Form onSubmit={handleSubmit}>
+            <div className={styles.text}>{t('common.newUsername')}</div>
+            <Input
+              fluid
+              ref={usernameField}
+              name="username"
+              value={data.username}
+              placeholder={username}
+              className={styles.field}
+              onChange={handleFieldChange}
+            />
+            {data.username.trim() !== (username || '') && (
+              <>
+                <div className={styles.text}>{t('common.currentPassword')}</div>
+                <Input.Password
+                  fluid
+                  ref={currentPasswordField}
+                  name="currentPassword"
+                  value={data.currentPassword}
+                  className={styles.field}
+                  onChange={handleFieldChange}
+                />
+              </>
+            )}
+            <Button
+              positive
+              content={t('action.save')}
+              loading={isSubmitting}
+              disabled={isSubmitting}
+            />
+          </Form>
+        </Popup.Content>
+      </>
+    );
+  },
+);
+
+EditUsernameStep.propTypes = {
+  defaultData: PropTypes.object.isRequired, // eslint-disable-line react/forbid-prop-types
+  username: PropTypes.string,
+  isSubmitting: PropTypes.bool.isRequired,
+  error: PropTypes.object, // eslint-disable-line react/forbid-prop-types
+  onUpdate: PropTypes.func.isRequired,
+  onMessageDismiss: PropTypes.func.isRequired,
+  onBack: PropTypes.func.isRequired,
+  onClose: PropTypes.func.isRequired,
+};
+
+EditUsernameStep.defaultProps = {
+  username: undefined,
+  error: undefined,
+};
+
+export default EditUsernameStep;
diff --git a/client/src/components/UserPopup/EditUsernameStep.module.css b/client/src/components/UserPopup/EditUsernameStep.module.css
new file mode 100644
index 00000000..72114a1d
--- /dev/null
+++ b/client/src/components/UserPopup/EditUsernameStep.module.css
@@ -0,0 +1,10 @@
+.field {
+  margin-bottom: 8px;
+}
+
+.text {
+  color: #444444;
+  font-size: 12px;
+  font-weight: bold;
+  padding-bottom: 6px;
+}
diff --git a/client/src/components/UserPopup/UserPopup.jsx b/client/src/components/UserPopup/UserPopup.jsx
index 34db3a38..bd624355 100755
--- a/client/src/components/UserPopup/UserPopup.jsx
+++ b/client/src/components/UserPopup/UserPopup.jsx
@@ -7,6 +7,7 @@ import { Popup } from '../../lib/custom-ui';
 
 import { useSteps } from '../../hooks';
 import EditNameStep from './EditNameStep';
+import EditUsernameStep from './EditUsernameStep';
 import EditAvatarStep from './EditAvatarStep';
 import EditEmailStep from './EditEmailStep';
 import EditPasswordStep from './EditPasswordStep';
@@ -15,6 +16,7 @@ import styles from './UserPopup.module.css';
 
 const StepTypes = {
   EDIT_NAME: 'EDIT_NAME',
+  EDIT_USERNAME: 'EDIT_USERNAME',
   EDIT_AVATAR: 'EDIT_AVATAR',
   EDIT_EMAIL: 'EDIT_EMAIL',
   EDIT_PASSWORD: 'EDIT_PASSWORD',
@@ -24,12 +26,16 @@ const UserStep = React.memo(
   ({
     email,
     name,
+    username,
     avatar,
     isAvatarUploading,
+    usernameUpdateForm,
     emailUpdateForm,
     passwordUpdateForm,
     onUpdate,
     onAvatarUpload,
+    onUsernameUpdate,
+    onUsernameUpdateMessageDismiss,
     onEmailUpdate,
     onEmailUpdateMessageDismiss,
     onPasswordUpdate,
@@ -48,6 +54,10 @@ const UserStep = React.memo(
       openStep(StepTypes.EDIT_AVATAR);
     }, [openStep]);
 
+    const handleUsernameEditClick = useCallback(() => {
+      openStep(StepTypes.EDIT_USERNAME);
+    }, [openStep]);
+
     const handleEmailEditClick = useCallback(() => {
       openStep(StepTypes.EDIT_EMAIL);
     }, [openStep]);
@@ -93,6 +103,19 @@ const UserStep = React.memo(
               onBack={handleBack}
             />
           );
+        case StepTypes.EDIT_USERNAME:
+          return (
+            <EditUsernameStep
+              defaultData={usernameUpdateForm.data}
+              username={username}
+              isSubmitting={usernameUpdateForm.isSubmitting}
+              error={usernameUpdateForm.error}
+              onUpdate={onUsernameUpdate}
+              onMessageDismiss={onUsernameUpdateMessageDismiss}
+              onBack={handleBack}
+              onClose={onClose}
+            />
+          );
         case StepTypes.EDIT_EMAIL:
           return (
             <EditEmailStep
@@ -124,7 +147,11 @@ const UserStep = React.memo(
 
     return (
       <>
-        <Popup.Header>{name}</Popup.Header>
+        <Popup.Header>
+          {t('common.userActions', {
+            context: 'title',
+          })}
+        </Popup.Header>
         <Popup.Content>
           <Menu secondary vertical className={styles.menu}>
             <Menu.Item className={styles.menuItem} onClick={handleNameEditClick}>
@@ -137,6 +164,11 @@ const UserStep = React.memo(
                 context: 'title',
               })}
             </Menu.Item>
+            <Menu.Item className={styles.menuItem} onClick={handleUsernameEditClick}>
+              {t('action.editUsername', {
+                context: 'title',
+              })}
+            </Menu.Item>
             <Menu.Item className={styles.menuItem} onClick={handleEmailEditClick}>
               {t('action.editEmail', {
                 context: 'title',
@@ -162,14 +194,18 @@ const UserStep = React.memo(
 UserStep.propTypes = {
   email: PropTypes.string.isRequired,
   name: PropTypes.string.isRequired,
+  username: PropTypes.string,
   avatar: PropTypes.string,
   isAvatarUploading: PropTypes.bool.isRequired,
   /* eslint-disable react/forbid-prop-types */
+  usernameUpdateForm: PropTypes.object.isRequired,
   emailUpdateForm: PropTypes.object.isRequired,
   passwordUpdateForm: PropTypes.object.isRequired,
   /* eslint-enable react/forbid-prop-types */
   onUpdate: PropTypes.func.isRequired,
   onAvatarUpload: PropTypes.func.isRequired,
+  onUsernameUpdate: PropTypes.func.isRequired,
+  onUsernameUpdateMessageDismiss: PropTypes.func.isRequired,
   onEmailUpdate: PropTypes.func.isRequired,
   onEmailUpdateMessageDismiss: PropTypes.func.isRequired,
   onPasswordUpdate: PropTypes.func.isRequired,
@@ -179,6 +215,7 @@ UserStep.propTypes = {
 };
 
 UserStep.defaultProps = {
+  username: undefined,
   avatar: undefined,
 };
 
diff --git a/client/src/components/UsersModal/Item.jsx b/client/src/components/UsersModal/Item.jsx
index f47107b3..4fb75b49 100755
--- a/client/src/components/UsersModal/Item.jsx
+++ b/client/src/components/UsersModal/Item.jsx
@@ -7,7 +7,7 @@ import DeletePopup from '../DeletePopup';
 
 import styles from './Item.module.css';
 
-const Item = React.memo(({ name, email, isAdmin, onUpdate, onDelete }) => {
+const Item = React.memo(({ name, username, email, isAdmin, onUpdate, onDelete }) => {
   const [t] = useTranslation();
 
   const handleIsAdminChange = useCallback(() => {
@@ -19,6 +19,7 @@ const Item = React.memo(({ name, email, isAdmin, onUpdate, onDelete }) => {
   return (
     <Table.Row>
       <Table.Cell>{name}</Table.Cell>
+      <Table.Cell>{username || '-'}</Table.Cell>
       <Table.Cell>{email}</Table.Cell>
       <Table.Cell collapsing>
         <Radio toggle checked={isAdmin} onChange={handleIsAdminChange} />
@@ -41,10 +42,15 @@ const Item = React.memo(({ name, email, isAdmin, onUpdate, onDelete }) => {
 
 Item.propTypes = {
   name: PropTypes.string.isRequired,
+  username: PropTypes.string,
   email: PropTypes.string.isRequired,
   isAdmin: PropTypes.bool.isRequired,
   onUpdate: PropTypes.func.isRequired,
   onDelete: PropTypes.func.isRequired,
 };
 
+Item.defaultProps = {
+  username: undefined,
+};
+
 export default Item;
diff --git a/client/src/components/UsersModal/UsersModal.jsx b/client/src/components/UsersModal/UsersModal.jsx
index ac0e698d..0a81b3af 100755
--- a/client/src/components/UsersModal/UsersModal.jsx
+++ b/client/src/components/UsersModal/UsersModal.jsx
@@ -34,8 +34,9 @@ const UsersModal = React.memo(({ items, onUpdate, onDelete, onClose }) => {
         <Table basic="very">
           <Table.Header>
             <Table.Row>
-              <Table.HeaderCell>{t('common.name')}</Table.HeaderCell>
-              <Table.HeaderCell>{t('common.email')}</Table.HeaderCell>
+              <Table.HeaderCell width={4}>{t('common.name')}</Table.HeaderCell>
+              <Table.HeaderCell width={4}>{t('common.username')}</Table.HeaderCell>
+              <Table.HeaderCell width={4}>{t('common.email')}</Table.HeaderCell>
               <Table.HeaderCell>{t('common.administrator')}</Table.HeaderCell>
               <Table.HeaderCell />
             </Table.Row>
@@ -45,6 +46,7 @@ const UsersModal = React.memo(({ items, onUpdate, onDelete, onClose }) => {
               <Item
                 key={item.id}
                 name={item.name}
+                username={item.username}
                 email={item.email}
                 isAdmin={item.isAdmin}
                 onUpdate={(data) => handleUpdate(item.id, data)}
diff --git a/client/src/constants/ActionTypes.js b/client/src/constants/ActionTypes.js
index 8782e2df..bce90049 100644
--- a/client/src/constants/ActionTypes.js
+++ b/client/src/constants/ActionTypes.js
@@ -34,6 +34,7 @@ export default {
   USER_UPDATE: 'USER_UPDATE',
   USER_EMAIL_UPDATE_ERROR_CLEAR: 'USER_EMAIL_UPDATE_ERROR_CLEAR',
   USER_PASSWORD_UPDATE_ERROR_CLEAR: 'USER_PASSWORD_UPDATE_ERROR_CLEAR',
+  USER_USERNAME_UPDATE_ERROR_CLEAR: 'USER_USERNAME_UPDATE_ERROR_CLEAR',
   USER_DELETE: 'USER_DELETE',
   USER_TO_CARD_ADD: 'USER_TO_CARD_ADD',
   USER_FROM_CARD_REMOVE: 'USER_FROM_CARD_REMOVE',
@@ -56,6 +57,9 @@ export default {
   USER_PASSWORD_UPDATE_REQUESTED: 'USER_PASSWORD_UPDATE_REQUESTED',
   USER_PASSWORD_UPDATE_SUCCEEDED: 'USER_PASSWORD_UPDATE_SUCCEEDED',
   USER_PASSWORD_UPDATE_FAILED: 'USER_PASSWORD_UPDATE_FAILED',
+  USER_USERNAME_UPDATE_REQUESTED: 'USER_USERNAME_UPDATE_REQUESTED',
+  USER_USERNAME_UPDATE_SUCCEEDED: 'USER_USERNAME_UPDATE_SUCCEEDED',
+  USER_USERNAME_UPDATE_FAILED: 'USER_USERNAME_UPDATE_FAILED',
   USER_AVATAR_UPLOAD_REQUESTED: 'USER_AVATAR_UPLOAD_REQUESTED',
   USER_AVATAR_UPLOAD_SUCCEEDED: 'USER_AVATAR_UPLOAD_SUCCEEDED',
   USER_AVATAR_UPLOAD_FAILED: 'USER_AVATAR_UPLOAD_FAILED',
diff --git a/client/src/constants/EntryActionTypes.js b/client/src/constants/EntryActionTypes.js
index 7549cfc0..757244f0 100755
--- a/client/src/constants/EntryActionTypes.js
+++ b/client/src/constants/EntryActionTypes.js
@@ -24,6 +24,8 @@ export default {
   CURRENT_USER_EMAIL_UPDATE_ERROR_CLEAR: `${PREFIX}/CURRENT_USER_EMAIL_UPDATE_ERROR_CLEAR`,
   CURRENT_USER_PASSWORD_UPDATE: `${PREFIX}/CURRENT_USER_PASSWORD_UPDATE`,
   CURRENT_USER_PASSWORD_UPDATE_ERROR_CLEAR: `${PREFIX}/CURRENT_USER_PASSWORD_UPDATE_ERROR_CLEAR`,
+  CURRENT_USER_USERNAME_UPDATE: `${PREFIX}/CURRENT_USER_USERNAME_UPDATE`,
+  CURRENT_USER_USERNAME_UPDATE_ERROR_CLEAR: `${PREFIX}/CURRENT_USER_USERNAME_UPDATE_ERROR_CLEAR`,
   CURRENT_USER_AVATAR_UPLOAD: `${PREFIX}/CURRENT_USER_AVATAR_UPLOAD`,
   USER_DELETE: `${PREFIX}/USER_DELETE`,
   USER_TO_CARD_ADD: `${PREFIX}/USER_TO_CARD_ADD`,
diff --git a/client/src/containers/HeaderContainer.js b/client/src/containers/HeaderContainer.js
index 2629dd54..6be09a07 100755
--- a/client/src/containers/HeaderContainer.js
+++ b/client/src/containers/HeaderContainer.js
@@ -5,12 +5,14 @@ import { currentUserSelector, notificationsForCurrentUserSelector } from '../sel
 import {
   clearCurrentUserEmailUpdateError,
   clearCurrentUserPasswordUpdateError,
+  clearCurrentUserUsernameUpdateError,
   deleteNotification,
   logout,
   openUsersModal,
   updateCurrentUser,
   updateCurrentUserEmail,
   updateCurrentUserPassword,
+  updateCurrentUserUsername,
   uploadCurrentUserAvatar,
 } from '../actions/entry';
 import Header from '../components/Header';
@@ -33,6 +35,8 @@ const mapDispatchToProps = (dispatch) =>
       onNotificationDelete: deleteNotification,
       onUserUpdate: updateCurrentUser,
       onUserAvatarUpload: uploadCurrentUserAvatar,
+      onUserUsernameUpdate: updateCurrentUserUsername,
+      onUserUsernameUpdateMessageDismiss: clearCurrentUserUsernameUpdateError,
       onUserEmailUpdate: updateCurrentUserEmail,
       onUserEmailUpdateMessageDismiss: clearCurrentUserEmailUpdateError,
       onUserPasswordUpdate: updateCurrentUserPassword,
diff --git a/client/src/locales/en-US/app.js b/client/src/locales/en-US/app.js
index 960df47c..162f3447 100644
--- a/client/src/locales/en-US/app.js
+++ b/client/src/locales/en-US/app.js
@@ -58,6 +58,9 @@ export default {
       editPassword_title: 'Edit Password',
       editProject_title: 'Edit Project',
       editTimer_title: 'Edit Timer',
+      editUsername_title: 'Edit Username',
+      email: 'E-mail',
+      emailAlreadyInUse: 'E-mail already in use',
       enterCardTitle: 'Enter card title...',
       enterDescription: 'Enter description...',
       enterListTitle: 'Enter list title...',
@@ -74,10 +77,12 @@ export default {
       name: 'Name',
       newEmail: 'New e-mail',
       newPassword: 'New password',
+      newUsername: 'New username',
       noConnectionToServer: 'No connection to server',
       notifications: 'Notifications',
       noUnreadNotifications: 'No unread notifications',
       openBoard_title: 'Open Board',
+      optional_inline: 'optional',
       projectNotFound_title: 'Project Not Found',
       refreshPageToLoadLastDataAndReceiveUpdates:
         '<0>Refresh the page</0> to load last data<br />and receive updates',
@@ -88,12 +93,14 @@ export default {
       time: 'Time',
       timer: 'Timer',
       title: 'Title',
+      userActions_title: 'User Actions',
       userAddedThisCardToList: '<0>{{user}}</0><1> added this card to {{list}}</1>',
-      userIsAlreadyExist: 'User is already exist',
       userLeftNewCommentToCard: '{{user}} left a new comment «{{comment}}» to <2>{{card}}</2>',
       userMovedCardFromListToList: '{{user}} moved <2>{{card}}</2> from {{fromList}} to {{toList}}',
       userMovedThisCardFromListToList:
         '<0>{{user}}</0><1> moved this card from {{fromList}} to {{toList}}</1>',
+      username: 'Username',
+      usernameAlreadyInUse: 'Username already in use',
       users: 'Users',
       writeComment: 'Write a comment...',
     },
@@ -137,6 +144,7 @@ export default {
       editTask_title: 'Edit Task',
       editTimer_title: 'Edit Timer',
       editTitle_title: 'Edit Title',
+      editUsername_title: 'Edit Username',
       logOut_title: 'Log Out',
       remove: 'Remove',
       removeFromProject: 'Remove from project',
diff --git a/client/src/locales/en-US/embed.js b/client/src/locales/en-US/embed.js
index e5234b8e..d7a1cd92 100644
--- a/client/src/locales/en-US/embed.js
+++ b/client/src/locales/en-US/embed.js
@@ -1,8 +1,8 @@
 export default {
   translation: {
     common: {
-      email: 'E-mail',
-      emailDoesNotExist: 'E-mail does not exist',
+      emailOrUsername: 'E-mail or username',
+      invalidEmailOrUsername: 'Invalid e-mail or username',
       invalidPassword: 'Invalid password',
       logInToPlanka: 'Log in to Planka',
       noInternetConnection: 'No internet connection',
diff --git a/client/src/locales/ru-RU/app.js b/client/src/locales/ru-RU/app.js
index aa87bc49..4a743429 100644
--- a/client/src/locales/ru-RU/app.js
+++ b/client/src/locales/ru-RU/app.js
@@ -62,6 +62,9 @@ export default {
       editPassword: 'Изменение пароля',
       editProject: 'Изменение проекта',
       editTimer: 'Изменение таймера',
+      editUsername: 'Изменение имени пользователя',
+      email: 'E-mail',
+      emailAlreadyInUse: 'E-mail уже занят',
       enterCardTitle: 'Введите заголовок для этой карточки...',
       enterDescription: 'Введите описание...',
       enterListTitle: 'Введите заголовок списка...',
@@ -78,10 +81,12 @@ export default {
       name: 'Имя',
       newEmail: 'Новый e-mail',
       newPassword: 'Новый пароль',
+      newUsername: 'Новое имя пользователя',
       noConnectionToServer: 'Нет соединения с сервером',
       notifications: 'Уведомления',
       noUnreadNotifications: 'Уведомлений нет',
       openBoard: 'Откройте доску',
+      optional_inline: 'необязательно',
       projectNotFound: 'Доска не найдена',
       refreshPageToLoadLastDataAndReceiveUpdates:
         '<0>Обновите страницу</0>, чтобы загрузить<br />актуальные данные и получать обновления',
@@ -92,13 +97,15 @@ export default {
       time: 'Время',
       timer: 'Таймер',
       title: 'Название',
+      userActions_title: 'Действия с пользователем',
       userAddedThisCardToList: '<0>{{user}}</0><1> добавил(а) эту карточку в {{list}}</1>',
-      userIsAlreadyExist: 'Пользователь уже существует',
       userLeftNewCommentToCard: '{{user}} оставил(а) комментарий «{{comment}}» к <2>{{card}}</2>',
       userMovedCardFromListToList:
         '{{user}} переместил(а) <2>{{card}}</2> из {{fromList}} в {{toList}}',
       userMovedThisCardFromListToList:
         '<0>{{user}}</0><1> переместил(а) эту карточку из {{fromList}} в {{toList}}</1>',
+      username: 'Имя пользователя',
+      usernameAlreadyInUse: 'Имя пользователя уже занято',
       users: 'Пользователи',
       writeComment: 'Напишите комментарий...',
     },
@@ -138,6 +145,7 @@ export default {
       editTask: 'Изменить задачу',
       editTimer: 'Изменить таймер',
       editTitle: 'Изменить название',
+      editUsername_title: 'Изменить имя пользователя',
       logOut: 'Выйти',
       remove: 'Убрать',
       removeFromProject: 'Удалить из проекта',
diff --git a/client/src/locales/ru-RU/embed.js b/client/src/locales/ru-RU/embed.js
index 6c549deb..2c06a4ff 100644
--- a/client/src/locales/ru-RU/embed.js
+++ b/client/src/locales/ru-RU/embed.js
@@ -1,8 +1,8 @@
 export default {
   translation: {
     common: {
-      email: 'E-mail',
-      emailDoesNotExist: 'Неверный e-mail',
+      emailOrUsername: 'E-mail или имя пользователя',
+      invalidEmailOrUsername: 'Неверный e-mail или имя пользователя',
       invalidPassword: 'Неверный пароль',
       logInToPlanka: 'Вход в Planka',
       noInternetConnection: 'Нет соединения',
diff --git a/client/src/models/User.js b/client/src/models/User.js
index e91d590e..9c0f154e 100755
--- a/client/src/models/User.js
+++ b/client/src/models/User.js
@@ -20,6 +20,15 @@ const DEFAULT_PASSWORD_UPDATE_FORM = {
   error: null,
 };
 
+const DEFAULT_USERNAME_UPDATE_FORM = {
+  data: {
+    username: '',
+    currentPassword: '',
+  },
+  isSubmitting: false,
+  error: null,
+};
+
 export default class extends Model {
   static modelName = 'User';
 
@@ -41,6 +50,9 @@ export default class extends Model {
     passwordUpdateForm: attr({
       getDefault: () => DEFAULT_PASSWORD_UPDATE_FORM,
     }),
+    usernameUpdateForm: attr({
+      getDefault: () => DEFAULT_USERNAME_UPDATE_FORM,
+    }),
   };
 
   static reducer({ type, payload }, User) {
@@ -92,6 +104,18 @@ export default class extends Model {
 
         break;
       }
+      case ActionTypes.USER_USERNAME_UPDATE_ERROR_CLEAR: {
+        const userModel = User.withId(payload.id);
+
+        userModel.update({
+          usernameUpdateForm: {
+            ...userModel.usernameUpdateForm,
+            error: null,
+          },
+        });
+
+        break;
+      }
       case ActionTypes.USER_DELETE:
         User.withId(payload.id).deleteWithRelated();
 
@@ -167,6 +191,40 @@ export default class extends Model {
 
         break;
       }
+      case ActionTypes.USER_USERNAME_UPDATE_REQUESTED: {
+        const userModel = User.withId(payload.id);
+
+        userModel.update({
+          usernameUpdateForm: {
+            ...userModel.usernameUpdateForm,
+            data: payload.data,
+            isSubmitting: true,
+          },
+        });
+
+        break;
+      }
+      case ActionTypes.USER_USERNAME_UPDATE_SUCCEEDED: {
+        User.withId(payload.id).update({
+          username: payload.username,
+          usernameUpdateForm: DEFAULT_USERNAME_UPDATE_FORM,
+        });
+
+        break;
+      }
+      case ActionTypes.USER_USERNAME_UPDATE_FAILED: {
+        const userModel = User.withId(payload.id);
+
+        userModel.update({
+          usernameUpdateForm: {
+            ...userModel.usernameUpdateForm,
+            isSubmitting: false,
+            error: payload.error,
+          },
+        });
+
+        break;
+      }
       case ActionTypes.USER_AVATAR_UPLOAD_REQUESTED:
         User.withId(payload.id).update({
           isAvatarUploading: true,
diff --git a/client/src/reducers/forms/authenticate.js b/client/src/reducers/forms/authenticate.js
index 612421e2..5bb03689 100644
--- a/client/src/reducers/forms/authenticate.js
+++ b/client/src/reducers/forms/authenticate.js
@@ -2,7 +2,7 @@ import ActionTypes from '../../constants/ActionTypes';
 
 const initialState = {
   data: {
-    email: '',
+    emailOrUsername: '',
     password: '',
   },
   isSubmitting: false,
diff --git a/client/src/reducers/forms/user-create.js b/client/src/reducers/forms/user-create.js
index 503bd679..5f4b18f9 100644
--- a/client/src/reducers/forms/user-create.js
+++ b/client/src/reducers/forms/user-create.js
@@ -4,6 +4,7 @@ const initialState = {
   data: {
     email: '',
     name: '',
+    username: '',
   },
   isSubmitting: false,
   error: null,
diff --git a/client/src/sagas/app/requests/user.js b/client/src/sagas/app/requests/user.js
index 7ddaef43..a394a97b 100644
--- a/client/src/sagas/app/requests/user.js
+++ b/client/src/sagas/app/requests/user.js
@@ -20,6 +20,9 @@ import {
   updateUserPasswordSucceeded,
   updateUserRequested,
   updateUserSucceeded,
+  updateUserUsernameFailed,
+  updateUserUsernameRequested,
+  updateUserUsernameSucceeded,
   uploadUserAvatarFailed,
   uploadUserAvatarRequested,
   uploadUserAvatarSucceeded,
@@ -146,6 +149,30 @@ export function* updateUserPasswordRequest(id, data) {
   }
 }
 
+export function* updateUserUsernameRequest(id, data) {
+  yield put(updateUserUsernameRequested(id, data));
+
+  try {
+    const { item } = yield call(request, api.updateUserUsername, id, data);
+
+    const action = updateUserUsernameSucceeded(id, item);
+    yield put(action);
+
+    return {
+      success: true,
+      payload: action.payload,
+    };
+  } catch (error) {
+    const action = updateUserUsernameFailed(id, error);
+    yield put(action);
+
+    return {
+      success: false,
+      payload: action.payload,
+    };
+  }
+}
+
 export function* uploadUserAvatarRequest(id, file) {
   yield put(uploadUserAvatarRequested(id));
 
diff --git a/client/src/sagas/app/services/user.js b/client/src/sagas/app/services/user.js
index bb264e39..d6cc0adb 100644
--- a/client/src/sagas/app/services/user.js
+++ b/client/src/sagas/app/services/user.js
@@ -8,6 +8,7 @@ import {
   updateUserEmailRequest,
   updateUserPasswordRequest,
   updateUserRequest,
+  updateUserUsernameRequest,
   uploadUserAvatarRequest,
 } from '../requests';
 import { currentUserIdSelector, pathSelector } from '../../../selectors';
@@ -17,6 +18,7 @@ import {
   clearUserCreateError,
   clearUserEmailUpdateError,
   clearUserPasswordUpdateError,
+  clearUserUsernameUpdateError,
   createUser,
   deleteUser,
   updateUser,
@@ -84,6 +86,26 @@ export function* clearCurrentUserPasswordUpdateErrorService() {
   yield call(clearUserPasswordUpdateErrorService, id);
 }
 
+export function* updateUserUsernameService(id, data) {
+  yield call(updateUserUsernameRequest, id, data);
+}
+
+export function* updateCurrentUserUsernameService(data) {
+  const id = yield select(currentUserIdSelector);
+
+  yield call(updateUserUsernameService, id, data);
+}
+
+export function* clearUserUsernameUpdateErrorService(id) {
+  yield put(clearUserUsernameUpdateError(id));
+}
+
+export function* clearCurrentUserUsernameUpdateErrorService() {
+  const id = yield select(currentUserIdSelector);
+
+  yield call(clearUserUsernameUpdateErrorService, id);
+}
+
 export function* uploadUserAvatarService(id, file) {
   yield call(uploadUserAvatarRequest, id, file);
 }
diff --git a/client/src/sagas/app/watchers/user.js b/client/src/sagas/app/watchers/user.js
index 41b3a48e..d66e4003 100644
--- a/client/src/sagas/app/watchers/user.js
+++ b/client/src/sagas/app/watchers/user.js
@@ -6,6 +6,7 @@ import {
   addUserToFilterInCurrentBoardService,
   clearCurrentUserEmailUpdateErrorService,
   clearCurrentUserPasswordUpdateErrorService,
+  clearCurrentUserUsernameUpdateErrorService,
   clearUserCreateErrorService,
   createUserService,
   deleteUserService,
@@ -16,6 +17,7 @@ import {
   updateCurrentUserEmailService,
   updateCurrentUserPasswordService,
   updateCurrentUserService,
+  updateCurrentUserUsernameService,
   uploadCurrentUserAvatarService,
 } from '../services';
 import EntryActionTypes from '../../../constants/EntryActionTypes';
@@ -42,6 +44,12 @@ export default function* () {
     takeLatest(EntryActionTypes.CURRENT_USER_PASSWORD_UPDATE_ERROR_CLEAR, () =>
       clearCurrentUserPasswordUpdateErrorService(),
     ),
+    takeLatest(EntryActionTypes.CURRENT_USER_USERNAME_UPDATE, ({ payload: { data } }) =>
+      updateCurrentUserUsernameService(data),
+    ),
+    takeLatest(EntryActionTypes.CURRENT_USER_USERNAME_UPDATE_ERROR_CLEAR, () =>
+      clearCurrentUserUsernameUpdateErrorService(),
+    ),
     takeLatest(EntryActionTypes.CURRENT_USER_AVATAR_UPLOAD, ({ payload: { file } }) =>
       uploadCurrentUserAvatarService(file),
     ),
diff --git a/client/src/utils/validator.js b/client/src/utils/validator.js
new file mode 100644
index 00000000..39bfaa2c
--- /dev/null
+++ b/client/src/utils/validator.js
@@ -0,0 +1,6 @@
+const USERNAME_REGEX = /^[a-zA-Z0-9]+(_?[a-zA-Z0-9])*$/;
+
+// eslint-disable-next-line import/prefer-default-export
+export const isUsername = (string) => {
+  return string.length >= 3 && string.length <= 16 && USERNAME_REGEX.test(string);
+};
diff --git a/server/api/controllers/access-tokens/create.js b/server/api/controllers/access-tokens/create.js
index 149cbab7..8b4ca0e3 100755
--- a/server/api/controllers/access-tokens/create.js
+++ b/server/api/controllers/access-tokens/create.js
@@ -1,20 +1,24 @@
 const bcrypt = require('bcrypt');
+const validator = require('validator');
 
 const Errors = {
-  EMAIL_NOT_EXIST: {
-    unauthorized: 'Email does not exist',
+  INVALID_EMAIL_OR_USERNAME: {
+    invalidEmailOrUsername: 'Invalid email or username',
   },
-  PASSWORD_NOT_VALID: {
-    unauthorized: 'Password is not valid',
+  INVALID_PASSWORD: {
+    invalidPassword: 'Invalid password',
   },
 };
 
 module.exports = {
   inputs: {
-    email: {
+    emailOrUsername: {
       type: 'string',
+      custom: (value) =>
+        value.includes('@')
+          ? validator.isEmail(value)
+          : value.length >= 3 && value.length <= 16 && /^[a-zA-Z0-9]+(_?[a-zA-Z0-9])*$/.test(value),
       required: true,
-      isEmail: true,
     },
     password: {
       type: 'string',
@@ -23,22 +27,23 @@ module.exports = {
   },
 
   exits: {
-    unauthorized: {
+    invalidEmailOrUsername: {
+      responseType: 'unauthorized',
+    },
+    invalidPassword: {
       responseType: 'unauthorized',
     },
   },
 
   async fn(inputs, exits) {
-    const user = await sails.helpers.getUser({
-      email: inputs.email.toLowerCase(),
-    });
+    const user = await sails.helpers.getUserByEmailOrUsername(inputs.emailOrUsername);
 
     if (!user) {
-      throw Errors.EMAIL_NOT_EXIST;
+      throw Errors.INVALID_EMAIL_OR_USERNAME;
     }
 
     if (!bcrypt.compareSync(inputs.password, user.password)) {
-      throw Errors.PASSWORD_NOT_VALID;
+      throw Errors.INVALID_PASSWORD;
     }
 
     return exits.success({
diff --git a/server/api/controllers/actions/index.js b/server/api/controllers/actions/index.js
index 61be3040..be5f3f4a 100755
--- a/server/api/controllers/actions/index.js
+++ b/server/api/controllers/actions/index.js
@@ -1,6 +1,6 @@
 const Errors = {
   CARD_NOT_FOUND: {
-    notFound: 'Card is not found',
+    cardNotFound: 'Card not found',
   },
 };
 
@@ -18,7 +18,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    cardNotFound: {
       responseType: 'notFound',
     },
   },
@@ -28,7 +28,7 @@ module.exports = {
 
     const { project } = await sails.helpers
       .getCardToProjectPath(inputs.cardId)
-      .intercept('notFound', () => Errors.CARD_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.CARD_NOT_FOUND);
 
     const isUserMemberForProject = await sails.helpers.isUserMemberForProject(
       project.id,
diff --git a/server/api/controllers/boards/create.js b/server/api/controllers/boards/create.js
index f5daa546..1510e56e 100755
--- a/server/api/controllers/boards/create.js
+++ b/server/api/controllers/boards/create.js
@@ -1,6 +1,6 @@
 const Errors = {
   PROJECT_NOT_FOUND: {
-    notFound: 'Project is not found',
+    projectNotFound: 'Project not found',
   },
 };
 
@@ -22,7 +22,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    projectNotFound: {
       responseType: 'notFound',
     },
   },
diff --git a/server/api/controllers/boards/delete.js b/server/api/controllers/boards/delete.js
index 58eea0ec..9987ba6b 100755
--- a/server/api/controllers/boards/delete.js
+++ b/server/api/controllers/boards/delete.js
@@ -1,6 +1,6 @@
 const Errors = {
   BOARD_NOT_FOUND: {
-    notFound: 'Board is not found',
+    boardNotFound: 'Board not found',
   },
 };
 
@@ -14,7 +14,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    boardNotFound: {
       responseType: 'notFound',
     },
   },
diff --git a/server/api/controllers/boards/show.js b/server/api/controllers/boards/show.js
index 67f59fd0..ace6d204 100755
--- a/server/api/controllers/boards/show.js
+++ b/server/api/controllers/boards/show.js
@@ -1,6 +1,6 @@
 const Errors = {
   BOARD_NOT_FOUND: {
-    notFound: 'Board is not found',
+    boardNotFound: 'Board not found',
   },
 };
 
@@ -14,7 +14,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    boardNotFound: {
       responseType: 'notFound',
     },
   },
@@ -29,7 +29,7 @@ module.exports = {
 
     const { board, project } = await sails.helpers
       .getBoardToProjectPath(inputs.id)
-      .intercept('notFound', () => Errors.BOARD_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.BOARD_NOT_FOUND);
 
     const isUserMemberForProject = await sails.helpers.isUserMemberForProject(
       project.id,
@@ -64,7 +64,7 @@ module.exports = {
       {},
     );
 
-    cards.map(card => ({
+    cards.map((card) => ({
       ...card,
       isSubscribed: isSubscribedByCardId[card.id] || false,
     }));
diff --git a/server/api/controllers/boards/update.js b/server/api/controllers/boards/update.js
index 885c93bb..f812e792 100755
--- a/server/api/controllers/boards/update.js
+++ b/server/api/controllers/boards/update.js
@@ -1,6 +1,6 @@
 const Errors = {
   BOARD_NOT_FOUND: {
-    notFound: 'Board is not found',
+    boardNotFound: 'Board not found',
   },
 };
 
@@ -21,7 +21,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    boardNotFound: {
       responseType: 'notFound',
     },
   },
diff --git a/server/api/controllers/card-labels/create.js b/server/api/controllers/card-labels/create.js
index 4f1f68a4..3d205342 100755
--- a/server/api/controllers/card-labels/create.js
+++ b/server/api/controllers/card-labels/create.js
@@ -1,12 +1,12 @@
 const Errors = {
   CARD_NOT_FOUND: {
-    notFound: 'Card is not found',
+    cardNotFound: 'Card not found',
   },
   LABEL_NOT_FOUND: {
-    notFound: 'Label is not found',
+    labelNotFound: 'Label not found',
   },
-  CARD_LABEL_EXIST: {
-    conflict: 'Card label is already exist',
+  LABEL_ALREADY_IN_CARD: {
+    labelAlreadyInCard: 'Label already in card',
   },
 };
 
@@ -25,10 +25,13 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    cardNotFound: {
       responseType: 'notFound',
     },
-    conflict: {
+    labelNotFound: {
+      responseType: 'notFound',
+    },
+    labelAlreadyInCard: {
       responseType: 'conflict',
     },
   },
@@ -38,7 +41,7 @@ module.exports = {
 
     const { card, project } = await sails.helpers
       .getCardToProjectPath(inputs.cardId)
-      .intercept('notFound', () => Errors.CARD_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.CARD_NOT_FOUND);
 
     const isUserMemberForProject = await sails.helpers.isUserMemberForProject(
       project.id,
@@ -60,7 +63,7 @@ module.exports = {
 
     const cardLabel = await sails.helpers
       .createCardLabel(card, label, this.req)
-      .intercept('conflict', () => Errors.CARD_LABEL_EXIST);
+      .intercept('labelAlreadyInCard', () => Errors.LABEL_ALREADY_IN_CARD);
 
     return exits.success({
       item: cardLabel,
diff --git a/server/api/controllers/card-labels/delete.js b/server/api/controllers/card-labels/delete.js
index 0b5e09a8..0fde5016 100755
--- a/server/api/controllers/card-labels/delete.js
+++ b/server/api/controllers/card-labels/delete.js
@@ -1,9 +1,9 @@
 const Errors = {
   CARD_NOT_FOUND: {
-    notFound: 'Card is not found',
+    cardNotFound: 'Card not found',
   },
-  CARD_LABEL_NOT_FOUND: {
-    notFound: 'Card label is not found',
+  LABEL_NOT_IN_CARD: {
+    labelNotInCard: 'Label not in card',
   },
 };
 
@@ -22,7 +22,10 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    cardNotFound: {
+      responseType: 'notFound',
+    },
+    labelNotInCard: {
       responseType: 'notFound',
     },
   },
@@ -32,7 +35,7 @@ module.exports = {
 
     const { board, project } = await sails.helpers
       .getCardToProjectPath(inputs.cardId)
-      .intercept('notFound', () => Errors.CARD_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.CARD_NOT_FOUND);
 
     const isUserMemberForProject = await sails.helpers.isUserMemberForProject(
       project.id,
@@ -49,13 +52,13 @@ module.exports = {
     });
 
     if (!cardLabel) {
-      throw Errors.CARD_LABEL_NOT_FOUND;
+      throw Errors.LABEL_NOT_IN_CARD;
     }
 
     cardLabel = await sails.helpers.deleteCardLabel(cardLabel, board, this.req);
 
     if (!cardLabel) {
-      throw Errors.CARD_LABEL_NOT_FOUND;
+      throw Errors.LABEL_NOT_IN_CARD;
     }
 
     return exits.success({
diff --git a/server/api/controllers/card-memberships/create.js b/server/api/controllers/card-memberships/create.js
index 7fe24e0e..3dfdf397 100755
--- a/server/api/controllers/card-memberships/create.js
+++ b/server/api/controllers/card-memberships/create.js
@@ -1,12 +1,12 @@
 const Errors = {
   CARD_NOT_FOUND: {
-    notFound: 'Card is not found',
+    cardNotFound: 'Card not found',
   },
   USER_NOT_FOUND: {
-    notFound: 'User is not found',
+    userNotFound: 'User not found',
   },
-  CARD_MEMBERSHIP_EXIST: {
-    conflict: 'Card membership is already exist',
+  USER_ALREADY_CARD_MEMBER: {
+    userAlreadyCardMember: 'User already card member',
   },
 };
 
@@ -25,10 +25,13 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    cardNotFound: {
       responseType: 'notFound',
     },
-    conflict: {
+    userNotFound: {
+      responseType: 'notFound',
+    },
+    userAlreadyCardMember: {
       responseType: 'conflict',
     },
   },
@@ -38,7 +41,7 @@ module.exports = {
 
     const { card, project } = await sails.helpers
       .getCardToProjectPath(inputs.cardId)
-      .intercept('notFound', () => Errors.CARD_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.CARD_NOT_FOUND);
 
     let isUserMemberForProject = await sails.helpers.isUserMemberForProject(
       project.id,
@@ -57,7 +60,7 @@ module.exports = {
 
     const cardMembership = await sails.helpers
       .createCardMembership(card, inputs.userId, this.req)
-      .intercept('conflict', () => Errors.CARD_MEMBERSHIP_EXIST);
+      .intercept('userAlreadyCardMember', () => Errors.USER_ALREADY_CARD_MEMBER);
 
     return exits.success({
       item: cardMembership,
diff --git a/server/api/controllers/card-memberships/delete.js b/server/api/controllers/card-memberships/delete.js
index fbc4a4fb..09b42e69 100755
--- a/server/api/controllers/card-memberships/delete.js
+++ b/server/api/controllers/card-memberships/delete.js
@@ -1,9 +1,9 @@
 const Errors = {
   CARD_NOT_FOUND: {
-    notFound: 'Card is not found',
+    cardNotFound: 'Card not found',
   },
-  CARD_MEMBERSHIP_NOT_FOUND: {
-    notFound: 'Card membership is not found',
+  USER_NOT_CARD_MEMBER: {
+    userNotCardMember: 'User not card member',
   },
 };
 
@@ -22,7 +22,10 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    cardNotFound: {
+      responseType: 'notFound',
+    },
+    userNotCardMember: {
       responseType: 'notFound',
     },
   },
@@ -32,7 +35,7 @@ module.exports = {
 
     const { board, project } = await sails.helpers
       .getCardToProjectPath(inputs.cardId)
-      .intercept('notFound', () => Errors.CARD_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.CARD_NOT_FOUND);
 
     const isUserMemberForProject = await sails.helpers.isUserMemberForProject(
       project.id,
@@ -49,13 +52,13 @@ module.exports = {
     });
 
     if (!cardMembership) {
-      throw Errors.CARD_MEMBERSHIP_NOT_FOUND;
+      throw Errors.USER_NOT_CARD_MEMBER;
     }
 
     cardMembership = await sails.helpers.deleteCardMembership(cardMembership, board, this.req);
 
     if (!cardMembership) {
-      throw Errors.CARD_MEMBERSHIP_NOT_FOUND;
+      throw Errors.USER_NOT_CARD_MEMBER;
     }
 
     return exits.success({
diff --git a/server/api/controllers/cards/create.js b/server/api/controllers/cards/create.js
index 36041d87..f8eefcab 100755
--- a/server/api/controllers/cards/create.js
+++ b/server/api/controllers/cards/create.js
@@ -2,7 +2,7 @@ const moment = require('moment');
 
 const Errors = {
   LIST_NOT_FOUND: {
-    notFound: 'List is not found',
+    listNotFound: 'List not found',
   },
 };
 
@@ -28,11 +28,11 @@ module.exports = {
     },
     dueDate: {
       type: 'string',
-      custom: value => moment(value, moment.ISO_8601, true).isValid(),
+      custom: (value) => moment(value, moment.ISO_8601, true).isValid(),
     },
     timer: {
       type: 'json',
-      custom: value =>
+      custom: (value) =>
         _.isPlainObject(value) &&
         _.size(value) === 2 &&
         (_.isNull(value.startedAt) || moment(value.startedAt, moment.ISO_8601, true).isValid()) &&
@@ -41,7 +41,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    listNotFound: {
       responseType: 'notFound',
     },
   },
@@ -51,7 +51,7 @@ module.exports = {
 
     const { list, project } = await sails.helpers
       .getListToProjectPath(inputs.listId)
-      .intercept('notFound', () => Errors.LIST_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.LIST_NOT_FOUND);
 
     const isUserMemberForProject = await sails.helpers.isUserMemberForProject(
       project.id,
diff --git a/server/api/controllers/cards/delete.js b/server/api/controllers/cards/delete.js
index c463ece5..7ee4eadc 100755
--- a/server/api/controllers/cards/delete.js
+++ b/server/api/controllers/cards/delete.js
@@ -1,6 +1,6 @@
 const Errors = {
   CARD_NOT_FOUND: {
-    notFound: 'Card is not found',
+    cardNotFound: 'Card not found',
   },
 };
 
@@ -14,7 +14,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    cardNotFound: {
       responseType: 'notFound',
     },
   },
@@ -24,7 +24,7 @@ module.exports = {
 
     const cardToProjectPath = await sails.helpers
       .getCardToProjectPath(inputs.id)
-      .intercept('notFound', () => Errors.CARD_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.CARD_NOT_FOUND);
 
     let { card } = cardToProjectPath;
     const { project } = cardToProjectPath;
diff --git a/server/api/controllers/cards/show.js b/server/api/controllers/cards/show.js
index a9949949..ddadb9fa 100755
--- a/server/api/controllers/cards/show.js
+++ b/server/api/controllers/cards/show.js
@@ -1,6 +1,6 @@
 const Errors = {
   CARD_NOT_FOUND: {
-    notFound: 'Card is not found',
+    cardNotFound: 'Card not found',
   },
 };
 
@@ -14,7 +14,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    cardNotFound: {
       responseType: 'notFound',
     },
   },
@@ -24,7 +24,7 @@ module.exports = {
 
     const { card, project } = await sails.helpers
       .getCardToProjectPath(inputs.id)
-      .intercept('notFound', () => Errors.CARD_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.CARD_NOT_FOUND);
 
     const isUserMemberForProject = await sails.helpers.isUserMemberForProject(
       project.id,
diff --git a/server/api/controllers/cards/update.js b/server/api/controllers/cards/update.js
index 24c4445a..37a63c3e 100755
--- a/server/api/controllers/cards/update.js
+++ b/server/api/controllers/cards/update.js
@@ -2,10 +2,10 @@ const moment = require('moment');
 
 const Errors = {
   CARD_NOT_FOUND: {
-    notFound: 'Card is not found',
+    cardNotFound: 'Card not found',
   },
   LIST_NOT_FOUND: {
-    notFound: 'List is not found',
+    listNotFound: 'List not found',
   },
 };
 
@@ -34,12 +34,12 @@ module.exports = {
     },
     dueDate: {
       type: 'string',
-      custom: value => moment(value, moment.ISO_8601, true).isValid(),
+      custom: (value) => moment(value, moment.ISO_8601, true).isValid(),
       allowNull: true,
     },
     timer: {
       type: 'json',
-      custom: value =>
+      custom: (value) =>
         _.isPlainObject(value) &&
         _.size(value) === 2 &&
         (_.isNull(value.startedAt) || moment(value.startedAt, moment.ISO_8601, true).isValid()) &&
@@ -51,7 +51,10 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    cardNotFound: {
+      responseType: 'notFound',
+    },
+    listNotFound: {
       responseType: 'notFound',
     },
   },
@@ -61,7 +64,7 @@ module.exports = {
 
     const cardToProjectPath = await sails.helpers
       .getCardToProjectPath(inputs.id)
-      .intercept('notFound', () => Errors.CARD_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.CARD_NOT_FOUND);
 
     let { card } = cardToProjectPath;
     const { list, project } = cardToProjectPath;
diff --git a/server/api/controllers/comment-actions/create.js b/server/api/controllers/comment-actions/create.js
index dd1eba8e..a5de36d7 100755
--- a/server/api/controllers/comment-actions/create.js
+++ b/server/api/controllers/comment-actions/create.js
@@ -1,6 +1,6 @@
 const Errors = {
   CARD_NOT_FOUND: {
-    notFound: 'Card is not found',
+    cardNotFound: 'Card not found',
   },
 };
 
@@ -18,7 +18,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    cardNotFound: {
       responseType: 'notFound',
     },
   },
@@ -28,7 +28,7 @@ module.exports = {
 
     const { card, project } = await sails.helpers
       .getCardToProjectPath(inputs.cardId)
-      .intercept('notFound', () => Errors.CARD_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.CARD_NOT_FOUND);
 
     const isUserMemberForProject = await sails.helpers.isUserMemberForProject(
       project.id,
diff --git a/server/api/controllers/comment-actions/delete.js b/server/api/controllers/comment-actions/delete.js
index a9846ccf..1434f1cb 100755
--- a/server/api/controllers/comment-actions/delete.js
+++ b/server/api/controllers/comment-actions/delete.js
@@ -1,6 +1,6 @@
 const Errors = {
   COMMENT_ACTION_NOT_FOUND: {
-    notFound: 'Comment action is not found',
+    commentActionNotFound: 'Comment action not found',
   },
 };
 
@@ -14,7 +14,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    commentActionNotFound: {
       responseType: 'notFound',
     },
   },
@@ -33,7 +33,7 @@ module.exports = {
 
     const actionToProjectPath = await sails.helpers
       .getActionToProjectPath(criteria)
-      .intercept('notFound', () => Errors.COMMENT_ACTION_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.COMMENT_ACTION_NOT_FOUND);
 
     let { action } = actionToProjectPath;
     const { board, project } = actionToProjectPath;
diff --git a/server/api/controllers/comment-actions/update.js b/server/api/controllers/comment-actions/update.js
index d97f3c03..9a995fae 100755
--- a/server/api/controllers/comment-actions/update.js
+++ b/server/api/controllers/comment-actions/update.js
@@ -1,6 +1,6 @@
 const Errors = {
   COMMENT_ACTION_NOT_FOUND: {
-    notFound: 'Comment action is not found',
+    commentActionNotFound: 'Comment action not found',
   },
 };
 
@@ -18,7 +18,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    commentActionNotFound: {
       responseType: 'notFound',
     },
   },
@@ -32,7 +32,7 @@ module.exports = {
         type: 'commentCard',
         userId: currentUser.id,
       })
-      .intercept('notFound', () => Errors.COMMENT_ACTION_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.COMMENT_ACTION_NOT_FOUND);
 
     let { action } = actionToProjectPath;
     const { board, project } = actionToProjectPath;
diff --git a/server/api/controllers/labels/create.js b/server/api/controllers/labels/create.js
index a6313524..2340012f 100755
--- a/server/api/controllers/labels/create.js
+++ b/server/api/controllers/labels/create.js
@@ -1,6 +1,6 @@
 const Errors = {
   BOARD_NOT_FOUND: {
-    notFound: 'Board is not found',
+    boardNotFound: 'Board not found',
   },
 };
 
@@ -24,7 +24,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    boardNotFound: {
       responseType: 'notFound',
     },
   },
@@ -34,7 +34,7 @@ module.exports = {
 
     const { board, project } = await sails.helpers
       .getBoardToProjectPath(inputs.boardId)
-      .intercept('notFound', () => Errors.BOARD_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.BOARD_NOT_FOUND);
 
     const isUserMemberForProject = await sails.helpers.isUserMemberForProject(
       project.id,
diff --git a/server/api/controllers/labels/delete.js b/server/api/controllers/labels/delete.js
index a6b013b9..f19159bd 100755
--- a/server/api/controllers/labels/delete.js
+++ b/server/api/controllers/labels/delete.js
@@ -1,6 +1,6 @@
 const Errors = {
   LABEL_NOT_FOUND: {
-    notFound: 'Label is not found',
+    labelNotFound: 'Label not found',
   },
 };
 
@@ -14,7 +14,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    labelNotFound: {
       responseType: 'notFound',
     },
   },
@@ -24,7 +24,7 @@ module.exports = {
 
     const labelToProjectPath = await sails.helpers
       .getLabelToProjectPath(inputs.id)
-      .intercept('notFound', () => Errors.LABEL_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.LABEL_NOT_FOUND);
 
     let { label } = labelToProjectPath;
     const { project } = labelToProjectPath;
diff --git a/server/api/controllers/labels/update.js b/server/api/controllers/labels/update.js
index 881a7b25..85fc305e 100755
--- a/server/api/controllers/labels/update.js
+++ b/server/api/controllers/labels/update.js
@@ -1,6 +1,6 @@
 const Errors = {
   LABEL_NOT_FOUND: {
-    notFound: 'Label is not found',
+    labelNotFound: 'Label not found',
   },
 };
 
@@ -24,7 +24,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    labelNotFound: {
       responseType: 'notFound',
     },
   },
@@ -34,7 +34,7 @@ module.exports = {
 
     const labelToProjectPath = await sails.helpers
       .getLabelToProjectPath(inputs.id)
-      .intercept('notFound', () => Errors.LABEL_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.LABEL_NOT_FOUND);
 
     let { label } = labelToProjectPath;
     const { project } = labelToProjectPath;
diff --git a/server/api/controllers/lists/create.js b/server/api/controllers/lists/create.js
index 6f0f3ff7..7acb5315 100755
--- a/server/api/controllers/lists/create.js
+++ b/server/api/controllers/lists/create.js
@@ -1,6 +1,6 @@
 const Errors = {
   BOARD_NOT_FOUND: {
-    notFound: 'Board is not found',
+    boardNotFound: 'Board not found',
   },
 };
 
@@ -22,7 +22,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    boardNotFound: {
       responseType: 'notFound',
     },
   },
@@ -32,7 +32,7 @@ module.exports = {
 
     const { board, project } = await sails.helpers
       .getBoardToProjectPath(inputs.boardId)
-      .intercept('notFound', () => Errors.BOARD_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.BOARD_NOT_FOUND);
 
     const isUserMemberForProject = await sails.helpers.isUserMemberForProject(
       project.id,
diff --git a/server/api/controllers/lists/delete.js b/server/api/controllers/lists/delete.js
index 4b323ac3..2fbaa0bf 100755
--- a/server/api/controllers/lists/delete.js
+++ b/server/api/controllers/lists/delete.js
@@ -1,6 +1,6 @@
 const Errors = {
   LIST_NOT_FOUND: {
-    notFound: 'List is not found',
+    listNotFound: 'List not found',
   },
 };
 
@@ -14,7 +14,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    listNotFound: {
       responseType: 'notFound',
     },
   },
@@ -24,7 +24,7 @@ module.exports = {
 
     const listToProjectPath = await sails.helpers
       .getListToProjectPath(inputs.id)
-      .intercept('notFound', () => Errors.LIST_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.LIST_NOT_FOUND);
 
     let { list } = listToProjectPath;
     const { project } = listToProjectPath;
diff --git a/server/api/controllers/lists/update.js b/server/api/controllers/lists/update.js
index 305296e1..31ef18c0 100755
--- a/server/api/controllers/lists/update.js
+++ b/server/api/controllers/lists/update.js
@@ -1,6 +1,6 @@
 const Errors = {
   LIST_NOT_FOUND: {
-    notFound: 'List is not found',
+    listNotFound: 'List not found',
   },
 };
 
@@ -21,7 +21,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    listNotFound: {
       responseType: 'notFound',
     },
   },
@@ -31,7 +31,7 @@ module.exports = {
 
     const listToProjectPath = await sails.helpers
       .getListToProjectPath(inputs.id)
-      .intercept('notFound', () => Errors.LIST_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.LIST_NOT_FOUND);
 
     let { list } = listToProjectPath;
     const { project } = listToProjectPath;
diff --git a/server/api/controllers/notifications/update.js b/server/api/controllers/notifications/update.js
index 1a8bcfc4..0b24206e 100755
--- a/server/api/controllers/notifications/update.js
+++ b/server/api/controllers/notifications/update.js
@@ -10,12 +10,6 @@ module.exports = {
     },
   },
 
-  exits: {
-    notFound: {
-      responseType: 'notFound',
-    },
-  },
-
   async fn(inputs, exits) {
     const { currentUser } = this.req;
 
diff --git a/server/api/controllers/project-memberships/create.js b/server/api/controllers/project-memberships/create.js
index 38d4c5ab..39b63d88 100755
--- a/server/api/controllers/project-memberships/create.js
+++ b/server/api/controllers/project-memberships/create.js
@@ -1,12 +1,12 @@
 const Errors = {
   PROJECT_NOT_FOUND: {
-    notFound: 'Project is not found',
+    projectNotFound: 'Project not found',
   },
   USER_NOT_FOUND: {
-    notFound: 'User is not found',
+    userNotFound: 'User not found',
   },
-  PROJECT_MEMBERSHIP_EXIST: {
-    conflict: 'Project membership is already exist',
+  USER_ALREADY_PROJECT_MEMBER: {
+    userAlreadyProjectMember: 'User already project member',
   },
 };
 
@@ -25,10 +25,13 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    projectNotFound: {
       responseType: 'notFound',
     },
-    conflict: {
+    userNotFound: {
+      responseType: 'notFound',
+    },
+    userAlreadyProjectMember: {
       responseType: 'conflict',
     },
   },
@@ -48,7 +51,7 @@ module.exports = {
 
     const projectMembership = await sails.helpers
       .createProjectMembership(project, user, this.req)
-      .intercept('conflict', () => Errors.PROJECT_MEMBERSHIP_EXIST);
+      .intercept('userAlreadyProjectMember', () => Errors.USER_ALREADY_PROJECT_MEMBER);
 
     return exits.success({
       item: projectMembership,
diff --git a/server/api/controllers/project-memberships/delete.js b/server/api/controllers/project-memberships/delete.js
index 188b0c17..61337741 100755
--- a/server/api/controllers/project-memberships/delete.js
+++ b/server/api/controllers/project-memberships/delete.js
@@ -1,6 +1,6 @@
 const Errors = {
   PROJECT_MEMBERSHIP_NOT_FOUND: {
-    notFound: 'Project membership is not found',
+    projectMembershipNotFound: 'Project membership not found',
   },
 };
 
@@ -14,7 +14,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    projectMembershipNotFound: {
       responseType: 'notFound',
     },
   },
diff --git a/server/api/controllers/projects/delete.js b/server/api/controllers/projects/delete.js
index b20dd4ac..ab901af0 100755
--- a/server/api/controllers/projects/delete.js
+++ b/server/api/controllers/projects/delete.js
@@ -1,6 +1,6 @@
 const Errors = {
   PROJECT_NOT_FOUND: {
-    notFound: 'Project is not found',
+    projectNotFound: 'Project not found',
   },
 };
 
@@ -14,7 +14,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    projectNotFound: {
       responseType: 'notFound',
     },
   },
diff --git a/server/api/controllers/projects/update.js b/server/api/controllers/projects/update.js
index fd93cc7e..ff82c5fe 100755
--- a/server/api/controllers/projects/update.js
+++ b/server/api/controllers/projects/update.js
@@ -1,6 +1,6 @@
 const Errors = {
   PROJECT_NOT_FOUND: {
-    notFound: 'Project is not found',
+    projectNotFound: 'Project not found',
   },
 };
 
@@ -18,7 +18,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    projectNotFound: {
       responseType: 'notFound',
     },
   },
diff --git a/server/api/controllers/tasks/create.js b/server/api/controllers/tasks/create.js
index 4c3d0c19..3ce5b4ae 100755
--- a/server/api/controllers/tasks/create.js
+++ b/server/api/controllers/tasks/create.js
@@ -1,6 +1,6 @@
 const Errors = {
   CARD_NOT_FOUND: {
-    notFound: 'Card is not found',
+    cardNotFound: 'Card not found',
   },
 };
 
@@ -21,7 +21,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    cardNotFound: {
       responseType: 'notFound',
     },
   },
@@ -31,7 +31,7 @@ module.exports = {
 
     const { card, project } = await sails.helpers
       .getCardToProjectPath(inputs.cardId)
-      .intercept('notFound', () => Errors.CARD_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.CARD_NOT_FOUND);
 
     const isUserMemberForProject = await sails.helpers.isUserMemberForProject(
       project.id,
diff --git a/server/api/controllers/tasks/delete.js b/server/api/controllers/tasks/delete.js
index f00deb0e..3e1b726f 100755
--- a/server/api/controllers/tasks/delete.js
+++ b/server/api/controllers/tasks/delete.js
@@ -1,6 +1,6 @@
 const Errors = {
   TASK_NOT_FOUND: {
-    notFound: 'Task is not found',
+    taskNotFound: 'Task not found',
   },
 };
 
@@ -14,7 +14,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    taskNotFound: {
       responseType: 'notFound',
     },
   },
@@ -24,7 +24,7 @@ module.exports = {
 
     const taskToProjectPath = await sails.helpers
       .getTaskToProjectPath(inputs.id)
-      .intercept('notFound', () => Errors.TASK_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.TASK_NOT_FOUND);
 
     let { task } = taskToProjectPath;
     const { board, project } = taskToProjectPath;
diff --git a/server/api/controllers/tasks/update.js b/server/api/controllers/tasks/update.js
index 0964d0ff..f2fd3f2e 100755
--- a/server/api/controllers/tasks/update.js
+++ b/server/api/controllers/tasks/update.js
@@ -1,6 +1,6 @@
 const Errors = {
   TASK_NOT_FOUND: {
-    notFound: 'Task is not found',
+    taskNotFound: 'Task not found',
   },
 };
 
@@ -21,7 +21,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    taskNotFound: {
       responseType: 'notFound',
     },
   },
@@ -31,7 +31,7 @@ module.exports = {
 
     const taskToProjectPath = await sails.helpers
       .getTaskToProjectPath(inputs.id)
-      .intercept('notFound', () => Errors.TASK_NOT_FOUND);
+      .intercept('pathNotFound', () => Errors.TASK_NOT_FOUND);
 
     let { task } = taskToProjectPath;
     const { board, project } = taskToProjectPath;
diff --git a/server/api/controllers/users/create.js b/server/api/controllers/users/create.js
index 96b5edda..2f8fba7a 100755
--- a/server/api/controllers/users/create.js
+++ b/server/api/controllers/users/create.js
@@ -1,6 +1,9 @@
 const Errors = {
-  USER_EXIST: {
-    conflict: 'User is already exist',
+  EMAIL_ALREADY_IN_USE: {
+    emailAlreadyInUse: 'Email already in use',
+  },
+  USERNAME_ALREADY_IN_USE: {
+    usernameAlreadyInUse: 'Username already in use',
   },
 };
 
@@ -19,20 +22,32 @@ module.exports = {
       type: 'string',
       required: true,
     },
+    username: {
+      type: 'string',
+      isNotEmptyString: true,
+      minLength: 3,
+      maxLength: 16,
+      regex: /^[a-zA-Z0-9]+(_?[a-zA-Z0-9])*$/,
+      allowNull: true,
+    },
   },
 
   exits: {
-    conflict: {
+    emailAlreadyInUse: {
+      responseType: 'conflict',
+    },
+    usernameAlreadyInUse: {
       responseType: 'conflict',
     },
   },
 
   async fn(inputs, exits) {
-    const values = _.pick(inputs, ['email', 'password', 'name']);
+    const values = _.pick(inputs, ['email', 'password', 'name', 'username']);
 
     const user = await sails.helpers
       .createUser(values, this.req)
-      .intercept('conflict', () => Errors.USER_EXIST);
+      .intercept('emailAlreadyInUse', () => Errors.EMAIL_ALREADY_IN_USE)
+      .intercept('usernameAlreadyInUse', () => Errors.USERNAME_ALREADY_IN_USE);
 
     return exits.success({
       item: user,
diff --git a/server/api/controllers/users/delete.js b/server/api/controllers/users/delete.js
index 96115fec..9171f407 100755
--- a/server/api/controllers/users/delete.js
+++ b/server/api/controllers/users/delete.js
@@ -1,6 +1,6 @@
 const Errors = {
   USER_NOT_FOUND: {
-    notFound: 'User is not found',
+    userNotFound: 'User not found',
   },
 };
 
@@ -14,7 +14,7 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    userNotFound: {
       responseType: 'notFound',
     },
   },
diff --git a/server/api/controllers/users/update-email.js b/server/api/controllers/users/update-email.js
index b01d8588..cda86f85 100644
--- a/server/api/controllers/users/update-email.js
+++ b/server/api/controllers/users/update-email.js
@@ -2,13 +2,13 @@ const bcrypt = require('bcrypt');
 
 const Errors = {
   USER_NOT_FOUND: {
-    notFound: 'User is not found',
+    userNotFound: 'User not found',
   },
-  CURRENT_PASSWORD_NOT_VALID: {
-    forbidden: 'Current password is not valid',
+  INVALID_CURRENT_PASSWORD: {
+    invalidCurrentPassword: 'Invalid current password',
   },
-  USER_EXIST: {
-    conflict: 'User is already exist',
+  EMAIL_ALREADY_IN_USE: {
+    emailAlreadyInUse: 'Email already in use',
   },
 };
 
@@ -31,13 +31,13 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    userNotFound: {
       responseType: 'notFound',
     },
-    forbidden: {
+    invalidCurrentPassword: {
       responseType: 'forbidden',
     },
-    conflict: {
+    emailAlreadyInUse: {
       responseType: 'conflict',
     },
   },
@@ -47,7 +47,7 @@ module.exports = {
 
     if (inputs.id === currentUser.id) {
       if (!inputs.currentPassword) {
-        throw Errors.CURRENT_PASSWORD_NOT_VALID;
+        throw Errors.INVALID_CURRENT_PASSWORD;
       }
     } else if (!currentUser.isAdmin) {
       throw Errors.USER_NOT_FOUND; // Forbidden
@@ -63,14 +63,14 @@ module.exports = {
       inputs.id === currentUser.id &&
       !bcrypt.compareSync(inputs.currentPassword, user.password)
     ) {
-      throw Errors.CURRENT_PASSWORD_NOT_VALID;
+      throw Errors.INVALID_CURRENT_PASSWORD;
     }
 
     const values = _.pick(inputs, ['email']);
 
     user = await sails.helpers
       .updateUser(user, values, this.req)
-      .intercept('conflict', () => Errors.USER_EXIST);
+      .intercept('emailAlreadyInUse', () => Errors.EMAIL_ALREADY_IN_USE);
 
     if (!user) {
       throw Errors.USER_NOT_FOUND;
diff --git a/server/api/controllers/users/update-password.js b/server/api/controllers/users/update-password.js
index 90e0dfcb..33bcce47 100644
--- a/server/api/controllers/users/update-password.js
+++ b/server/api/controllers/users/update-password.js
@@ -2,10 +2,10 @@ const bcrypt = require('bcrypt');
 
 const Errors = {
   USER_NOT_FOUND: {
-    notFound: 'User is not found',
+    userNotFound: 'User not found',
   },
-  CURRENT_PASSWORD_NOT_VALID: {
-    forbidden: 'Current password is not valid',
+  INVALID_CURRENT_PASSWORD: {
+    invalidCurrentPassword: 'Invalid current password',
   },
 };
 
@@ -27,10 +27,10 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    userNotFound: {
       responseType: 'notFound',
     },
-    forbidden: {
+    invalidCurrentPassword: {
       responseType: 'forbidden',
     },
   },
@@ -40,7 +40,7 @@ module.exports = {
 
     if (inputs.id === currentUser.id) {
       if (!inputs.currentPassword) {
-        throw Errors.CURRENT_PASSWORD_NOT_VALID;
+        throw Errors.INVALID_CURRENT_PASSWORD;
       }
     } else if (!currentUser.isAdmin) {
       throw Errors.USER_NOT_FOUND; // Forbidden
@@ -56,7 +56,7 @@ module.exports = {
       inputs.id === currentUser.id &&
       !bcrypt.compareSync(inputs.currentPassword, user.password)
     ) {
-      throw Errors.CURRENT_PASSWORD_NOT_VALID;
+      throw Errors.INVALID_CURRENT_PASSWORD;
     }
 
     const values = _.pick(inputs, ['password']);
diff --git a/server/api/controllers/users/update-username.js b/server/api/controllers/users/update-username.js
new file mode 100644
index 00000000..13110e2a
--- /dev/null
+++ b/server/api/controllers/users/update-username.js
@@ -0,0 +1,85 @@
+const bcrypt = require('bcrypt');
+
+const Errors = {
+  USER_NOT_FOUND: {
+    userNotFound: 'User not found',
+  },
+  INVALID_CURRENT_PASSWORD: {
+    invalidCurrentPassword: 'Invalid current password',
+  },
+  USERNAME_ALREADY_IN_USE: {
+    usernameAlreadyInUse: 'Username already in use',
+  },
+};
+
+module.exports = {
+  inputs: {
+    id: {
+      type: 'string',
+      regex: /^[0-9]+$/,
+      required: true,
+    },
+    username: {
+      isNotEmptyString: true,
+      minLength: 3,
+      maxLength: 16,
+      regex: /^[a-zA-Z0-9]+(_?[a-zA-Z0-9])*$/,
+      allowNull: true,
+    },
+    currentPassword: {
+      type: 'string',
+      isNotEmptyString: true,
+    },
+  },
+
+  exits: {
+    userNotFound: {
+      responseType: 'notFound',
+    },
+    invalidCurrentPassword: {
+      responseType: 'forbidden',
+    },
+    usernameAlreadyInUse: {
+      responseType: 'conflict',
+    },
+  },
+
+  async fn(inputs, exits) {
+    const { currentUser } = this.req;
+
+    if (inputs.id === currentUser.id) {
+      if (!inputs.currentPassword) {
+        throw Errors.INVALID_CURRENT_PASSWORD;
+      }
+    } else if (!currentUser.isAdmin) {
+      throw Errors.USER_NOT_FOUND; // Forbidden
+    }
+
+    let user = await sails.helpers.getUser(inputs.id);
+
+    if (!user) {
+      throw Errors.USER_NOT_FOUND;
+    }
+
+    if (
+      inputs.id === currentUser.id &&
+      !bcrypt.compareSync(inputs.currentPassword, user.password)
+    ) {
+      throw Errors.INVALID_CURRENT_PASSWORD;
+    }
+
+    const values = _.pick(inputs, ['username']);
+
+    user = await sails.helpers
+      .updateUser(user, values, this.req)
+      .intercept('usernameAlreadyInUse', () => Errors.USERNAME_ALREADY_IN_USE);
+
+    if (!user) {
+      throw Errors.USER_NOT_FOUND;
+    }
+
+    return exits.success({
+      item: user.username,
+    });
+  },
+};
diff --git a/server/api/controllers/users/update.js b/server/api/controllers/users/update.js
index 2a6f0a1d..d8e4cf9d 100755
--- a/server/api/controllers/users/update.js
+++ b/server/api/controllers/users/update.js
@@ -1,6 +1,6 @@
 const Errors = {
   USER_NOT_FOUND: {
-    notFound: 'User is not found',
+    userNotFound: 'User not found',
   },
 };
 
@@ -20,12 +20,12 @@ module.exports = {
     },
     avatar: {
       type: 'json',
-      custom: value => _.isNull(value),
+      custom: (value) => _.isNull(value),
     },
   },
 
   exits: {
-    notFound: {
+    userNotFound: {
       responseType: 'notFound',
     },
   },
diff --git a/server/api/controllers/users/upload-avatar.js b/server/api/controllers/users/upload-avatar.js
index 0b36f266..c362e7c1 100755
--- a/server/api/controllers/users/upload-avatar.js
+++ b/server/api/controllers/users/upload-avatar.js
@@ -7,7 +7,7 @@ const sharp = require('sharp');
 
 const Errors = {
   USER_NOT_FOUND: {
-    notFound: 'User is not found',
+    userNotFound: 'User not found',
   },
 };
 
@@ -32,9 +32,7 @@ const createReceiver = () => {
     }
     firstFileHandled = true;
 
-    const resize = sharp()
-      .resize(36, 36)
-      .jpeg();
+    const resize = sharp().resize(36, 36).jpeg();
 
     const transform = new stream.Transform({
       transform(chunk, streamEncoding, callback) {
@@ -71,10 +69,10 @@ module.exports = {
   },
 
   exits: {
-    notFound: {
+    userNotFound: {
       responseType: 'notFound',
     },
-    unprocessableEntity: {
+    uploadError: {
       responseType: 'unprocessableEntity',
     },
   },
@@ -97,11 +95,11 @@ module.exports = {
 
     this.req.file('file').upload(createReceiver(), async (error, files) => {
       if (error) {
-        return exits.unprocessableEntity(error.message);
+        return exits.uploadError(error.message);
       }
 
       if (files.length === 0) {
-        return exits.unprocessableEntity('No file was uploaded');
+        return exits.uploadError('No file was uploaded');
       }
 
       user = await sails.helpers.updateUser(
diff --git a/server/api/helpers/create-action.js b/server/api/helpers/create-action.js
index 52b3f41e..ca9cef70 100644
--- a/server/api/helpers/create-action.js
+++ b/server/api/helpers/create-action.js
@@ -35,7 +35,7 @@ module.exports = {
 
     const userIds = await sails.helpers.getSubscriptionUserIdsForCard(action.cardId, action.userId);
 
-    userIds.forEach(async userId => {
+    userIds.forEach(async (userId) => {
       const notification = await Notification.create({
         userId,
         actionId: action.id,
diff --git a/server/api/helpers/create-board.js b/server/api/helpers/create-board.js
index 5067a5f6..78702453 100644
--- a/server/api/helpers/create-board.js
+++ b/server/api/helpers/create-board.js
@@ -6,7 +6,7 @@ module.exports = {
     },
     values: {
       type: 'json',
-      custom: value => _.isPlainObject(value) && _.isFinite(value.position),
+      custom: (value) => _.isPlainObject(value) && _.isFinite(value.position),
       required: true,
     },
     request: {
@@ -32,7 +32,7 @@ module.exports = {
         position: nextPosition,
       });
 
-      userIds.forEach(userId => {
+      userIds.forEach((userId) => {
         sails.sockets.broadcast(`user:${userId}`, 'boardUpdate', {
           item: {
             id,
@@ -48,7 +48,7 @@ module.exports = {
       projectId: inputs.project.id,
     }).fetch();
 
-    userIds.forEach(userId => {
+    userIds.forEach((userId) => {
       sails.sockets.broadcast(
         `user:${userId}`,
         'boardCreate',
diff --git a/server/api/helpers/create-card-label.js b/server/api/helpers/create-card-label.js
index b67c7258..7be9058e 100644
--- a/server/api/helpers/create-card-label.js
+++ b/server/api/helpers/create-card-label.js
@@ -13,12 +13,16 @@ module.exports = {
     },
   },
 
+  exits: {
+    labelAlreadyInCard: {},
+  },
+
   async fn(inputs, exits) {
     const cardLabel = await CardLabel.create({
       cardId: inputs.card.id,
       labelId: inputs.label.id,
     })
-      .intercept('E_UNIQUE', 'conflict')
+      .intercept('E_UNIQUE', 'labelAlreadyInCard')
       .fetch();
 
     sails.sockets.broadcast(
diff --git a/server/api/helpers/create-card-membership.js b/server/api/helpers/create-card-membership.js
index e352e47a..bcdd8574 100644
--- a/server/api/helpers/create-card-membership.js
+++ b/server/api/helpers/create-card-membership.js
@@ -6,7 +6,7 @@ module.exports = {
     },
     userOrUserId: {
       type: 'ref',
-      custom: value => _.isPlainObject(value) || _.isString(value),
+      custom: (value) => _.isPlainObject(value) || _.isString(value),
       required: true,
     },
     request: {
@@ -14,6 +14,10 @@ module.exports = {
     },
   },
 
+  exits: {
+    userAlreadyCardMember: {},
+  },
+
   async fn(inputs, exits) {
     const { userId = inputs.userOrUserId } = inputs.userOrUserId;
 
@@ -21,7 +25,7 @@ module.exports = {
       userId,
       cardId: inputs.card.id,
     })
-      .intercept('E_UNIQUE', 'conflict')
+      .intercept('E_UNIQUE', 'userAlreadyCardMember')
       .fetch();
 
     sails.sockets.broadcast(
diff --git a/server/api/helpers/create-card.js b/server/api/helpers/create-card.js
index cd36556f..435c81f1 100644
--- a/server/api/helpers/create-card.js
+++ b/server/api/helpers/create-card.js
@@ -6,7 +6,7 @@ module.exports = {
     },
     values: {
       type: 'json',
-      custom: value => _.isPlainObject(value) && _.isFinite(value.position),
+      custom: (value) => _.isPlainObject(value) && _.isFinite(value.position),
       required: true,
     },
     user: {
diff --git a/server/api/helpers/create-list.js b/server/api/helpers/create-list.js
index 5f9609d0..e76ae135 100644
--- a/server/api/helpers/create-list.js
+++ b/server/api/helpers/create-list.js
@@ -6,7 +6,7 @@ module.exports = {
     },
     values: {
       type: 'json',
-      custom: value => _.isPlainObject(value) && _.isFinite(value.position),
+      custom: (value) => _.isPlainObject(value) && _.isFinite(value.position),
       required: true,
     },
     request: {
diff --git a/server/api/helpers/create-project-membership.js b/server/api/helpers/create-project-membership.js
index 779636a0..6395b87f 100644
--- a/server/api/helpers/create-project-membership.js
+++ b/server/api/helpers/create-project-membership.js
@@ -14,7 +14,7 @@ module.exports = {
   },
 
   exits: {
-    conflict: {},
+    userAlreadyProjectMember: {},
   },
 
   async fn(inputs, exits) {
@@ -22,7 +22,7 @@ module.exports = {
       projectId: inputs.project.id,
       userId: inputs.user.id,
     })
-      .intercept('E_UNIQUE', 'conflict')
+      .intercept('E_UNIQUE', 'userAlreadyProjectMember')
       .fetch();
 
     const { userIds, projectMemberships } = await sails.helpers.getMembershipUserIdsForProject(
@@ -30,7 +30,7 @@ module.exports = {
       true,
     );
 
-    userIds.forEach(userId => {
+    userIds.forEach((userId) => {
       if (userId !== projectMembership.userId) {
         sails.sockets.broadcast(
           `user:${userId}`,
diff --git a/server/api/helpers/create-user.js b/server/api/helpers/create-user.js
index ec964966..4d2951ab 100644
--- a/server/api/helpers/create-user.js
+++ b/server/api/helpers/create-user.js
@@ -4,8 +4,11 @@ module.exports = {
   inputs: {
     values: {
       type: 'json',
-      custom: value =>
-        _.isPlainObject(value) && _.isString(value.email) && _.isString(value.password),
+      custom: (value) =>
+        _.isPlainObject(value) &&
+        _.isString(value.email) &&
+        _.isString(value.password) &&
+        (!value.username || _.isString(value.username)),
       required: true,
     },
     request: {
@@ -14,10 +17,16 @@ module.exports = {
   },
 
   exits: {
-    conflict: {},
+    emailAlreadyInUse: {},
+    usernameAlreadyInUse: {},
   },
 
   async fn(inputs, exits) {
+    if (inputs.values.username) {
+      // eslint-disable-next-line no-param-reassign
+      inputs.values.username = inputs.values.username.toLowerCase();
+    }
+
     const user = await User.create({
       ...inputs.values,
       email: inputs.values.email.toLowerCase(),
@@ -28,13 +37,20 @@ module.exports = {
           message:
             'Unexpected error from database adapter: conflicting key value violates exclusion constraint "user_email_unique"',
         },
-        'conflict',
+        'emailAlreadyInUse',
+      )
+      .intercept(
+        {
+          message:
+            'Unexpected error from database adapter: conflicting key value violates exclusion constraint "user_username_unique"',
+        },
+        'usernameAlreadyInUse',
       )
       .fetch();
 
     const userIds = await sails.helpers.getAdminUserIds();
 
-    userIds.forEach(userId => {
+    userIds.forEach((userId) => {
       sails.sockets.broadcast(
         `user:${userId}`,
         'userCreate',
diff --git a/server/api/helpers/delete-board.js b/server/api/helpers/delete-board.js
index 09805106..027c26a7 100644
--- a/server/api/helpers/delete-board.js
+++ b/server/api/helpers/delete-board.js
@@ -17,7 +17,7 @@ module.exports = {
 
       const userIds = await sails.helpers.getMembershipUserIdsForProject(board.projectId);
 
-      userIds.forEach(userId => {
+      userIds.forEach((userId) => {
         sails.sockets.broadcast(
           `user:${userId}`,
           'boardDelete',
diff --git a/server/api/helpers/delete-project-membership.js b/server/api/helpers/delete-project-membership.js
index b04a8a43..0ab32bc7 100644
--- a/server/api/helpers/delete-project-membership.js
+++ b/server/api/helpers/delete-project-membership.js
@@ -34,7 +34,7 @@ module.exports = {
         projectMembership.projectId,
       );
 
-      userIds.forEach(userId => {
+      userIds.forEach((userId) => {
         sails.sockets.broadcast(
           `user:${userId}`,
           'projectMembershipDelete',
@@ -47,7 +47,7 @@ module.exports = {
 
       sails.sockets.removeRoomMembersFromRooms(
         `user:${projectMembership.userId}`,
-        boardIds.map(boardId => `board:${boardId}`),
+        boardIds.map((boardId) => `board:${boardId}`),
       );
 
       const project = await Project.findOne(projectMembership.projectId);
diff --git a/server/api/helpers/delete-project.js b/server/api/helpers/delete-project.js
index 1e1b4f6b..5b236c95 100644
--- a/server/api/helpers/delete-project.js
+++ b/server/api/helpers/delete-project.js
@@ -20,9 +20,9 @@ module.exports = {
       const userIds = sails.helpers.mapRecords(projectMemberships, 'userId');
 
       const boards = await sails.helpers.getBoardsForProject(project.id);
-      const boardRooms = boards.map(board => `board:${board.id}`);
+      const boardRooms = boards.map((board) => `board:${board.id}`);
 
-      userIds.forEach(userId => {
+      userIds.forEach((userId) => {
         sails.sockets.removeRoomMembersFromRooms(`user:${userId}`, boardRooms);
 
         sails.sockets.broadcast(
diff --git a/server/api/helpers/delete-user.js b/server/api/helpers/delete-user.js
index 986ebdab..1af5ed9b 100644
--- a/server/api/helpers/delete-user.js
+++ b/server/api/helpers/delete-user.js
@@ -38,7 +38,7 @@ module.exports = {
 
       const userIds = _.union([user.id], adminUserIds, userIdsForProject);
 
-      userIds.forEach(userId => {
+      userIds.forEach((userId) => {
         sails.sockets.broadcast(
           `user:${userId}`,
           'userDelete',
diff --git a/server/api/helpers/get-action-to-project-path.js b/server/api/helpers/get-action-to-project-path.js
index 1ddce65f..d9a8bdfb 100755
--- a/server/api/helpers/get-action-to-project-path.js
+++ b/server/api/helpers/get-action-to-project-path.js
@@ -7,20 +7,20 @@ module.exports = {
   },
 
   exits: {
-    notFound: {},
+    pathNotFound: {},
   },
 
   async fn(inputs, exits) {
     const action = await Action.findOne(inputs.criteria);
 
     if (!action) {
-      throw 'notFound';
+      throw 'pathNotFound';
     }
 
     const path = await sails.helpers
       .getCardToProjectPath(action.cardId)
-      .intercept('notFound', nodes => ({
-        notFound: {
+      .intercept('pathNotFound', (nodes) => ({
+        pathNotFound: {
           action,
           ...nodes,
         },
diff --git a/server/api/helpers/get-actions-for-card.js b/server/api/helpers/get-actions-for-card.js
index c0989961..4044a4b1 100644
--- a/server/api/helpers/get-actions-for-card.js
+++ b/server/api/helpers/get-actions-for-card.js
@@ -4,7 +4,7 @@ module.exports = {
   inputs: {
     id: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
       required: true,
     },
     beforeId: {
diff --git a/server/api/helpers/get-actions.js b/server/api/helpers/get-actions.js
index 58ed9c59..1d05a0b6 100644
--- a/server/api/helpers/get-actions.js
+++ b/server/api/helpers/get-actions.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     criteria: {
       type: 'json',
-      custom: value => _.isArray(value) || _.isPlainObject(value),
+      custom: (value) => _.isArray(value) || _.isPlainObject(value),
     },
     limit: {
       type: 'number',
@@ -10,9 +10,7 @@ module.exports = {
   },
 
   async fn(inputs, exits) {
-    const actions = await Action.find(inputs.criteria)
-      .sort('id DESC')
-      .limit(inputs.limit);
+    const actions = await Action.find(inputs.criteria).sort('id DESC').limit(inputs.limit);
 
     return exits.success(actions);
   },
diff --git a/server/api/helpers/get-board-to-project-path.js b/server/api/helpers/get-board-to-project-path.js
index 0a7b539f..a98e44be 100755
--- a/server/api/helpers/get-board-to-project-path.js
+++ b/server/api/helpers/get-board-to-project-path.js
@@ -7,21 +7,21 @@ module.exports = {
   },
 
   exits: {
-    notFound: {},
+    pathNotFound: {},
   },
 
   async fn(inputs, exits) {
     const board = await Board.findOne(inputs.criteria);
 
     if (!board) {
-      throw 'notFound';
+      throw 'pathNotFound';
     }
 
     const project = await Project.findOne(board.projectId);
 
     if (!project) {
       throw {
-        notFound: {
+        pathNotFound: {
           board,
         },
       };
diff --git a/server/api/helpers/get-boards-for-project.js b/server/api/helpers/get-boards-for-project.js
index f8c2fb32..9e8aebb2 100644
--- a/server/api/helpers/get-boards-for-project.js
+++ b/server/api/helpers/get-boards-for-project.js
@@ -2,12 +2,12 @@ module.exports = {
   inputs: {
     id: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
       required: true,
     },
     exceptBoardId: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
     },
   },
 
diff --git a/server/api/helpers/get-boards.js b/server/api/helpers/get-boards.js
index c78bf7ab..d7b4ff95 100644
--- a/server/api/helpers/get-boards.js
+++ b/server/api/helpers/get-boards.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     criteria: {
       type: 'json',
-      custom: value => _.isArray(value) || _.isPlainObject(value),
+      custom: (value) => _.isArray(value) || _.isPlainObject(value),
     },
   },
 
diff --git a/server/api/helpers/get-card-labels-for-card.js b/server/api/helpers/get-card-labels-for-card.js
index 5e7e3b16..62fbcced 100644
--- a/server/api/helpers/get-card-labels-for-card.js
+++ b/server/api/helpers/get-card-labels-for-card.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     id: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
       required: true,
     },
   },
diff --git a/server/api/helpers/get-card-labels.js b/server/api/helpers/get-card-labels.js
index 9662d873..82622e6c 100644
--- a/server/api/helpers/get-card-labels.js
+++ b/server/api/helpers/get-card-labels.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     criteria: {
       type: 'json',
-      custom: value => _.isArray(value) || _.isPlainObject(value),
+      custom: (value) => _.isArray(value) || _.isPlainObject(value),
     },
   },
 
diff --git a/server/api/helpers/get-card-memberships.js b/server/api/helpers/get-card-memberships.js
index a4ccb940..a5ac2ac4 100644
--- a/server/api/helpers/get-card-memberships.js
+++ b/server/api/helpers/get-card-memberships.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     criteria: {
       type: 'json',
-      custom: value => _.isArray(value) || _.isPlainObject(value),
+      custom: (value) => _.isArray(value) || _.isPlainObject(value),
     },
   },
 
diff --git a/server/api/helpers/get-card-subscriptions.js b/server/api/helpers/get-card-subscriptions.js
index f727fa28..d46cc1e6 100644
--- a/server/api/helpers/get-card-subscriptions.js
+++ b/server/api/helpers/get-card-subscriptions.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     criteria: {
       type: 'json',
-      custom: value => _.isArray(value) || _.isPlainObject(value),
+      custom: (value) => _.isArray(value) || _.isPlainObject(value),
     },
   },
 
diff --git a/server/api/helpers/get-card-to-project-path.js b/server/api/helpers/get-card-to-project-path.js
index 6186219c..cdf2506b 100755
--- a/server/api/helpers/get-card-to-project-path.js
+++ b/server/api/helpers/get-card-to-project-path.js
@@ -7,20 +7,20 @@ module.exports = {
   },
 
   exits: {
-    notFound: {},
+    pathNotFound: {},
   },
 
   async fn(inputs, exits) {
     const card = await Card.findOne(inputs.criteria);
 
     if (!card) {
-      throw 'notFound';
+      throw 'pathNotFound';
     }
 
     const path = await sails.helpers
       .getListToProjectPath(card.listId)
-      .intercept('notFound', nodes => ({
-        notFound: {
+      .intercept('pathNotFound', (nodes) => ({
+        pathNotFound: {
           card,
           ...nodes,
         },
diff --git a/server/api/helpers/get-cards-for-board.js b/server/api/helpers/get-cards-for-board.js
index 847920d2..6dcd8bdc 100644
--- a/server/api/helpers/get-cards-for-board.js
+++ b/server/api/helpers/get-cards-for-board.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     id: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
       required: true,
     },
   },
diff --git a/server/api/helpers/get-cards-for-list.js b/server/api/helpers/get-cards-for-list.js
index 5020a209..7668d9cd 100644
--- a/server/api/helpers/get-cards-for-list.js
+++ b/server/api/helpers/get-cards-for-list.js
@@ -2,12 +2,12 @@ module.exports = {
   inputs: {
     id: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
       required: true,
     },
     exceptCardId: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
     },
   },
 
diff --git a/server/api/helpers/get-cards.js b/server/api/helpers/get-cards.js
index 234d44ea..f347e666 100644
--- a/server/api/helpers/get-cards.js
+++ b/server/api/helpers/get-cards.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     criteria: {
       type: 'json',
-      custom: value => _.isArray(value) || _.isPlainObject(value),
+      custom: (value) => _.isArray(value) || _.isPlainObject(value),
     },
   },
 
diff --git a/server/api/helpers/get-label-to-project-path.js b/server/api/helpers/get-label-to-project-path.js
index d0303fd2..7e9f031d 100755
--- a/server/api/helpers/get-label-to-project-path.js
+++ b/server/api/helpers/get-label-to-project-path.js
@@ -7,20 +7,20 @@ module.exports = {
   },
 
   exits: {
-    notFound: {},
+    pathNotFound: {},
   },
 
   async fn(inputs, exits) {
     const label = await Label.findOne(inputs.criteria);
 
     if (!label) {
-      throw 'notFound';
+      throw 'pathNotFound';
     }
 
     const path = await sails.helpers
       .getBoardToProjectPath(label.boardId)
-      .intercept('notFound', nodes => ({
-        notFound: {
+      .intercept('pathNotFound', (nodes) => ({
+        pathNotFound: {
           label,
           ...nodes,
         },
diff --git a/server/api/helpers/get-labels-for-board.js b/server/api/helpers/get-labels-for-board.js
index e3b310e2..b5aaf3dd 100644
--- a/server/api/helpers/get-labels-for-board.js
+++ b/server/api/helpers/get-labels-for-board.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     id: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
       required: true,
     },
   },
diff --git a/server/api/helpers/get-list-to-project-path.js b/server/api/helpers/get-list-to-project-path.js
index 97068b86..955bf341 100755
--- a/server/api/helpers/get-list-to-project-path.js
+++ b/server/api/helpers/get-list-to-project-path.js
@@ -7,20 +7,20 @@ module.exports = {
   },
 
   exits: {
-    notFound: {},
+    pathNotFound: {},
   },
 
   async fn(inputs, exits) {
     const list = await List.findOne(inputs.criteria);
 
     if (!list) {
-      throw 'notFound';
+      throw 'pathNotFound';
     }
 
     const path = await sails.helpers
       .getBoardToProjectPath(list.boardId)
-      .intercept('notFound', nodes => ({
-        notFound: {
+      .intercept('pathNotFound', (nodes) => ({
+        pathNotFound: {
           list,
           ...nodes,
         },
diff --git a/server/api/helpers/get-lists-for-board.js b/server/api/helpers/get-lists-for-board.js
index d82745e7..49d1d354 100644
--- a/server/api/helpers/get-lists-for-board.js
+++ b/server/api/helpers/get-lists-for-board.js
@@ -2,12 +2,12 @@ module.exports = {
   inputs: {
     id: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
       required: true,
     },
     exceptListId: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
     },
   },
 
diff --git a/server/api/helpers/get-membership-project-ids-for-user.js b/server/api/helpers/get-membership-project-ids-for-user.js
index 9618ad24..e11b68d5 100755
--- a/server/api/helpers/get-membership-project-ids-for-user.js
+++ b/server/api/helpers/get-membership-project-ids-for-user.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     id: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
       required: true,
     },
   },
diff --git a/server/api/helpers/get-membership-user-ids-for-project.js b/server/api/helpers/get-membership-user-ids-for-project.js
index 41a9936e..405868fc 100755
--- a/server/api/helpers/get-membership-user-ids-for-project.js
+++ b/server/api/helpers/get-membership-user-ids-for-project.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     id: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
       required: true,
     },
     withProjectMemberships: {
diff --git a/server/api/helpers/get-memberships-for-card.js b/server/api/helpers/get-memberships-for-card.js
index a8284ad8..86c26a4b 100644
--- a/server/api/helpers/get-memberships-for-card.js
+++ b/server/api/helpers/get-memberships-for-card.js
@@ -2,12 +2,12 @@ module.exports = {
   inputs: {
     id: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
       required: true,
     },
     exceptUserId: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
     },
   },
 
diff --git a/server/api/helpers/get-memberships-for-project.js b/server/api/helpers/get-memberships-for-project.js
index 88385d1d..9f294ca8 100644
--- a/server/api/helpers/get-memberships-for-project.js
+++ b/server/api/helpers/get-memberships-for-project.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     id: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
       required: true,
     },
   },
diff --git a/server/api/helpers/get-notifications-for-user.js b/server/api/helpers/get-notifications-for-user.js
index cbd2ebd4..6138e5c8 100644
--- a/server/api/helpers/get-notifications-for-user.js
+++ b/server/api/helpers/get-notifications-for-user.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     id: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
       required: true,
     },
   },
diff --git a/server/api/helpers/get-notifications.js b/server/api/helpers/get-notifications.js
index 0c51e0ee..a08e6356 100644
--- a/server/api/helpers/get-notifications.js
+++ b/server/api/helpers/get-notifications.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     criteria: {
       type: 'json',
-      custom: value => _.isArray(value) || _.isPlainObject(value),
+      custom: (value) => _.isArray(value) || _.isPlainObject(value),
     },
   },
 
diff --git a/server/api/helpers/get-project-memberships-for-user.js b/server/api/helpers/get-project-memberships-for-user.js
index 27f33d6f..02999055 100644
--- a/server/api/helpers/get-project-memberships-for-user.js
+++ b/server/api/helpers/get-project-memberships-for-user.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     id: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
       required: true,
     },
   },
diff --git a/server/api/helpers/get-project-memberships.js b/server/api/helpers/get-project-memberships.js
index a9fca16e..20b17c6e 100644
--- a/server/api/helpers/get-project-memberships.js
+++ b/server/api/helpers/get-project-memberships.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     criteria: {
       type: 'json',
-      custom: value => _.isArray(value) || _.isPlainObject(value),
+      custom: (value) => _.isArray(value) || _.isPlainObject(value),
     },
   },
 
diff --git a/server/api/helpers/get-projects.js b/server/api/helpers/get-projects.js
index 98c94f47..6218e1b7 100644
--- a/server/api/helpers/get-projects.js
+++ b/server/api/helpers/get-projects.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     criteria: {
       type: 'json',
-      custom: value => _.isArray(value) || _.isPlainObject(value),
+      custom: (value) => _.isArray(value) || _.isPlainObject(value),
     },
   },
 
diff --git a/server/api/helpers/get-subscription-user-ids-for-card.js b/server/api/helpers/get-subscription-user-ids-for-card.js
index d276ee3e..e6fa0cd8 100644
--- a/server/api/helpers/get-subscription-user-ids-for-card.js
+++ b/server/api/helpers/get-subscription-user-ids-for-card.js
@@ -2,12 +2,12 @@ module.exports = {
   inputs: {
     id: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
       required: true,
     },
     exceptUserId: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
     },
     withCardSubscriptions: {
       type: 'boolean',
diff --git a/server/api/helpers/get-subscriptions-by-user-for-card.js b/server/api/helpers/get-subscriptions-by-user-for-card.js
index 349b3302..632733de 100644
--- a/server/api/helpers/get-subscriptions-by-user-for-card.js
+++ b/server/api/helpers/get-subscriptions-by-user-for-card.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     id: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
       required: true,
     },
     userId: {
diff --git a/server/api/helpers/get-subscriptions-for-card.js b/server/api/helpers/get-subscriptions-for-card.js
index e3d43f1d..7874b602 100644
--- a/server/api/helpers/get-subscriptions-for-card.js
+++ b/server/api/helpers/get-subscriptions-for-card.js
@@ -2,12 +2,12 @@ module.exports = {
   inputs: {
     id: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
       required: true,
     },
     exceptUserId: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
     },
   },
 
diff --git a/server/api/helpers/get-task-to-project-path.js b/server/api/helpers/get-task-to-project-path.js
index 3cfe722d..b3416bf3 100755
--- a/server/api/helpers/get-task-to-project-path.js
+++ b/server/api/helpers/get-task-to-project-path.js
@@ -7,20 +7,20 @@ module.exports = {
   },
 
   exits: {
-    notFound: {},
+    pathNotFound: {},
   },
 
   async fn(inputs, exits) {
     const task = await Task.findOne(inputs.criteria);
 
     if (!task) {
-      throw 'notFound';
+      throw 'pathNotFound';
     }
 
     const path = await sails.helpers
       .getCardToProjectPath(task.cardId)
-      .intercept('notFound', nodes => ({
-        notFound: {
+      .intercept('pathNotFound', (nodes) => ({
+        pathNotFound: {
           task,
           ...nodes,
         },
diff --git a/server/api/helpers/get-tasks-for-card.js b/server/api/helpers/get-tasks-for-card.js
index ceeec159..29a8ac5b 100644
--- a/server/api/helpers/get-tasks-for-card.js
+++ b/server/api/helpers/get-tasks-for-card.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     id: {
       type: 'json',
-      custom: value => _.isString(value) || _.isArray(value),
+      custom: (value) => _.isString(value) || _.isArray(value),
       required: true,
     },
   },
diff --git a/server/api/helpers/get-tasks.js b/server/api/helpers/get-tasks.js
index be4cd739..50ea0605 100644
--- a/server/api/helpers/get-tasks.js
+++ b/server/api/helpers/get-tasks.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     criteria: {
       type: 'json',
-      custom: value => _.isArray(value) || _.isPlainObject(value),
+      custom: (value) => _.isArray(value) || _.isPlainObject(value),
     },
   },
 
diff --git a/server/api/helpers/get-user-by-email-or-username.js b/server/api/helpers/get-user-by-email-or-username.js
new file mode 100644
index 00000000..ef423f6e
--- /dev/null
+++ b/server/api/helpers/get-user-by-email-or-username.js
@@ -0,0 +1,18 @@
+module.exports = {
+  inputs: {
+    emailOrUsername: {
+      type: 'string',
+      required: true,
+    },
+  },
+
+  async fn(inputs, exits) {
+    const fieldName = inputs.emailOrUsername.includes('@') ? 'email' : 'username';
+
+    const user = await sails.helpers.getUser({
+      [fieldName]: inputs.emailOrUsername.toLowerCase(),
+    });
+
+    return exits.success(user);
+  },
+};
diff --git a/server/api/helpers/get-user.js b/server/api/helpers/get-user.js
index 08ea1c9c..1a0320e2 100644
--- a/server/api/helpers/get-user.js
+++ b/server/api/helpers/get-user.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     criteria: {
       type: 'json',
-      custom: value => _.isString(value) || _.isPlainObject(value),
+      custom: (value) => _.isString(value) || _.isPlainObject(value),
       required: true,
     },
   },
diff --git a/server/api/helpers/get-users.js b/server/api/helpers/get-users.js
index ed816d15..b52eb81d 100644
--- a/server/api/helpers/get-users.js
+++ b/server/api/helpers/get-users.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     criteria: {
       type: 'json',
-      custom: value => _.isArray(value) || _.isPlainObject(value),
+      custom: (value) => _.isArray(value) || _.isPlainObject(value),
     },
   },
 
diff --git a/server/api/helpers/insert-to-positionables.js b/server/api/helpers/insert-to-positionables.js
index 0a0a4655..581dd1f0 100755
--- a/server/api/helpers/insert-to-positionables.js
+++ b/server/api/helpers/insert-to-positionables.js
@@ -2,14 +2,14 @@ const GAP = 2 ** 14;
 const MIN_GAP = 0.125;
 const MAX_POSITION = 2 ** 50;
 
-const findBeginnings = positions => {
+const findBeginnings = (positions) => {
   positions.unshift(0);
 
   let prevPosition = positions.pop();
   const beginnings = [prevPosition];
 
   // eslint-disable-next-line consistent-return
-  _.forEachRight(positions, position => {
+  _.forEachRight(positions, (position) => {
     if (prevPosition - MIN_GAP >= position) {
       return false;
     }
@@ -21,7 +21,7 @@ const findBeginnings = positions => {
   return beginnings;
 };
 
-const getRepositionsMap = positions => {
+const getRepositionsMap = (positions) => {
   const repositionsMap = {};
 
   if (positions.length <= 1) {
@@ -62,7 +62,7 @@ const getRepositionsMap = positions => {
   return repositionsMap;
 };
 
-const getFullRepositionsMap = positions => {
+const getFullRepositionsMap = (positions) => {
   const repositionsMap = {};
 
   _.forEach(positions, (position, index) => {
diff --git a/server/api/helpers/map-records.js b/server/api/helpers/map-records.js
index b4e814ca..25aea0e0 100644
--- a/server/api/helpers/map-records.js
+++ b/server/api/helpers/map-records.js
@@ -4,7 +4,7 @@ module.exports = {
   inputs: {
     records: {
       type: 'ref',
-      custom: value => _.isArray(value),
+      custom: (value) => _.isArray(value),
       required: true,
     },
     attribute: {
diff --git a/server/api/helpers/update-board.js b/server/api/helpers/update-board.js
index 67f67010..37755fe5 100644
--- a/server/api/helpers/update-board.js
+++ b/server/api/helpers/update-board.js
@@ -6,7 +6,7 @@ module.exports = {
     },
     values: {
       type: 'json',
-      custom: value =>
+      custom: (value) =>
         _.isPlainObject(value) && (_.isUndefined(value.position) || _.isFinite(value.position)),
       required: true,
     },
@@ -39,7 +39,7 @@ module.exports = {
           position: nextPosition,
         });
 
-        userIds.forEach(userId => {
+        userIds.forEach((userId) => {
           sails.sockets.broadcast(`user:${userId}`, 'boardUpdate', {
             item: {
               id,
@@ -53,7 +53,7 @@ module.exports = {
     const board = await Board.updateOne(inputs.record.id).set(inputs.values);
 
     if (board) {
-      userIds.forEach(userId => {
+      userIds.forEach((userId) => {
         sails.sockets.broadcast(
           `user:${userId}`,
           'boardUpdate',
diff --git a/server/api/helpers/update-card.js b/server/api/helpers/update-card.js
index 8771532e..f82ce765 100644
--- a/server/api/helpers/update-card.js
+++ b/server/api/helpers/update-card.js
@@ -6,7 +6,7 @@ module.exports = {
     },
     values: {
       type: 'json',
-      custom: value =>
+      custom: (value) =>
         _.isPlainObject(value) && (_.isUndefined(value.position) || _.isFinite(value.position)),
       required: true,
     },
diff --git a/server/api/helpers/update-list.js b/server/api/helpers/update-list.js
index 174dafcc..fdb76cc8 100644
--- a/server/api/helpers/update-list.js
+++ b/server/api/helpers/update-list.js
@@ -6,7 +6,7 @@ module.exports = {
     },
     values: {
       type: 'json',
-      custom: value =>
+      custom: (value) =>
         _.isPlainObject(value) && (_.isUndefined(value.position) || _.isFinite(value.position)),
       required: true,
     },
diff --git a/server/api/helpers/update-notifications-for-user.js b/server/api/helpers/update-notifications-for-user.js
index 026586cd..8945824b 100644
--- a/server/api/helpers/update-notifications-for-user.js
+++ b/server/api/helpers/update-notifications-for-user.js
@@ -2,7 +2,7 @@ module.exports = {
   inputs: {
     ids: {
       type: 'json',
-      custom: value => _.isArray(value),
+      custom: (value) => _.isArray(value),
       required: true,
     },
     user: {
@@ -26,7 +26,7 @@ module.exports = {
       .set(inputs.values)
       .fetch();
 
-    notifications.forEach(notification => {
+    notifications.forEach((notification) => {
       sails.sockets.broadcast(
         `user:${notification.userId}`,
         'notificationUpdate',
diff --git a/server/api/helpers/update-project.js b/server/api/helpers/update-project.js
index f1575362..a32ffb27 100644
--- a/server/api/helpers/update-project.js
+++ b/server/api/helpers/update-project.js
@@ -19,7 +19,7 @@ module.exports = {
     if (project) {
       const userIds = await sails.helpers.getMembershipUserIdsForProject(project.id);
 
-      userIds.forEach(userId => {
+      userIds.forEach((userId) => {
         sails.sockets.broadcast(
           `user:${userId}`,
           'projectUpdate',
diff --git a/server/api/helpers/update-user.js b/server/api/helpers/update-user.js
index ba655534..c678f055 100644
--- a/server/api/helpers/update-user.js
+++ b/server/api/helpers/update-user.js
@@ -10,10 +10,11 @@ module.exports = {
     },
     values: {
       type: 'json',
-      custom: value =>
+      custom: (value) =>
         _.isPlainObject(value) &&
         (_.isUndefined(value.email) || _.isString(value.email)) &&
-        (_.isUndefined(value.password) || _.isString(value.password)),
+        (_.isUndefined(value.password) || _.isString(value.password)) &&
+        (!value.username || _.isString(value.username)),
       required: true,
     },
     request: {
@@ -22,7 +23,8 @@ module.exports = {
   },
 
   exits: {
-    conflict: {},
+    emailAlreadyInUse: {},
+    usernameAlreadyInUse: {},
   },
 
   async fn(inputs, exits) {
@@ -42,6 +44,11 @@ module.exports = {
       }
     }
 
+    if (inputs.values.username) {
+      // eslint-disable-next-line no-param-reassign
+      inputs.values.username = inputs.values.username.toLowerCase();
+    }
+
     const user = await User.updateOne({
       id: inputs.record.id,
       deletedAt: null,
@@ -52,7 +59,14 @@ module.exports = {
           message:
             'Unexpected error from database adapter: conflicting key value violates exclusion constraint "user_email_unique"',
         },
-        'conflict',
+        'emailAlreadyInUse',
+      )
+      .intercept(
+        {
+          message:
+            'Unexpected error from database adapter: conflicting key value violates exclusion constraint "user_username_unique"',
+        },
+        'usernameAlreadyInUse',
       );
 
     if (user) {
@@ -73,7 +87,7 @@ module.exports = {
 
         const userIds = _.union([user.id], adminUserIds, userIdsForProject);
 
-        userIds.forEach(userId => {
+        userIds.forEach((userId) => {
           sails.sockets.broadcast(
             `user:${userId}`,
             'userUpdate',
diff --git a/server/api/helpers/verify-token.js b/server/api/helpers/verify-token.js
index 28aa4c21..61285fb4 100755
--- a/server/api/helpers/verify-token.js
+++ b/server/api/helpers/verify-token.js
@@ -11,7 +11,7 @@ module.exports = {
   },
 
   exits: {
-    notValid: {},
+    invalidToken: {},
   },
 
   fn(inputs, exits) {
@@ -20,7 +20,7 @@ module.exports = {
     try {
       payload = jwt.verify(inputs.token, sails.config.session.secret);
     } catch (error) {
-      throw 'notValid';
+      throw 'invalidToken';
     }
 
     return exits.success(payload);
diff --git a/server/api/hooks/current-user/index.js b/server/api/hooks/current-user/index.js
index 845f0c8b..4fca82b9 100644
--- a/server/api/hooks/current-user/index.js
+++ b/server/api/hooks/current-user/index.js
@@ -9,7 +9,7 @@
 module.exports = function defineCurrentUserHook(sails) {
   const TOKEN_PATTERN = /^Bearer /;
 
-  const getUser = async accessToken => {
+  const getUser = async (accessToken) => {
     let id;
 
     try {
diff --git a/server/api/models/User.js b/server/api/models/User.js
index d843a88e..e4f929e7 100755
--- a/server/api/models/User.js
+++ b/server/api/models/User.js
@@ -29,6 +29,14 @@ module.exports = {
       type: 'string',
       required: true,
     },
+    username: {
+      type: 'string',
+      isNotEmptyString: true,
+      minLength: 3,
+      maxLength: 16,
+      regex: /^[a-zA-Z0-9]+(_?[a-zA-Z0-9])*$/,
+      allowNull: true,
+    },
     avatar: {
       type: 'string',
       isNotEmptyString: true,
diff --git a/server/config/routes.js b/server/config/routes.js
index 263ab212..3e8596d0 100644
--- a/server/config/routes.js
+++ b/server/config/routes.js
@@ -17,6 +17,7 @@ module.exports.routes = {
   'PATCH /api/users/:id': 'users/update',
   'PATCH /api/users/:id/email': 'users/update-email',
   'PATCH /api/users/:id/password': 'users/update-password',
+  'PATCH /api/users/:id/username': 'users/update-username',
   'POST /api/users/:id/upload-avatar': 'users/upload-avatar',
   'DELETE /api/users/:id': 'users/delete',
 
diff --git a/server/db/migrations/20180721020022_create_next_id_function.js b/server/db/migrations/20180721020022_create_next_id_function.js
index 809ac349..649663d2 100644
--- a/server/db/migrations/20180721020022_create_next_id_function.js
+++ b/server/db/migrations/20180721020022_create_next_id_function.js
@@ -1,4 +1,4 @@
-module.exports.up = knex =>
+module.exports.up = (knex) =>
   knex.raw(`
     CREATE SEQUENCE next_id_seq;
 
@@ -20,7 +20,7 @@ module.exports.up = knex =>
     $$ LANGUAGE PLPGSQL;
   `);
 
-module.exports.down = knex =>
+module.exports.down = (knex) =>
   knex.raw(`
     DROP SEQUENCE next_id_seq;
     DROP FUNCTION next_id(OUT id BIGINT);
diff --git a/server/db/migrations/20180721021044_create_archive_table.js b/server/db/migrations/20180721021044_create_archive_table.js
index b0dbf352..9c609142 100755
--- a/server/db/migrations/20180721021044_create_archive_table.js
+++ b/server/db/migrations/20180721021044_create_archive_table.js
@@ -1,11 +1,8 @@
-module.exports.up = knex =>
-  knex.schema.createTable('archive', table => {
+module.exports.up = (knex) =>
+  knex.schema.createTable('archive', (table) => {
     /* Columns */
 
-    table
-      .bigInteger('id')
-      .primary()
-      .defaultTo(knex.raw('next_id()'));
+    table.bigInteger('id').primary().defaultTo(knex.raw('next_id()'));
 
     table.text('from_model').notNullable();
     table.bigInteger('original_record_id').notNullable();
@@ -19,4 +16,4 @@ module.exports.up = knex =>
     table.unique(['from_model', 'original_record_id']);
   });
 
-module.exports.down = knex => knex.schema.dropTable('archive');
+module.exports.down = (knex) => knex.schema.dropTable('archive');
diff --git a/server/db/migrations/20180721220409_create_user_account_table.js b/server/db/migrations/20180721220409_create_user_account_table.js
index f1f8f212..1fd26b36 100755
--- a/server/db/migrations/20180721220409_create_user_account_table.js
+++ b/server/db/migrations/20180721220409_create_user_account_table.js
@@ -1,17 +1,15 @@
-module.exports.up = knex =>
+module.exports.up = (knex) =>
   knex.schema
-    .createTable('user_account', table => {
+    .createTable('user_account', (table) => {
       /* Columns */
 
-      table
-        .bigInteger('id')
-        .primary()
-        .defaultTo(knex.raw('next_id()'));
+      table.bigInteger('id').primary().defaultTo(knex.raw('next_id()'));
 
       table.text('email').notNullable();
       table.text('password').notNullable();
       table.boolean('is_admin').notNullable();
       table.text('name').notNullable();
+      table.text('username');
       table.text('avatar');
 
       table.timestamp('created_at', true);
@@ -20,6 +18,9 @@ module.exports.up = knex =>
     })
     .raw(
       'ALTER TABLE "user_account" ADD CONSTRAINT "user_email_unique" EXCLUDE ("email" WITH =) WHERE ("deleted_at" IS NULL)',
+    )
+    .raw(
+      'ALTER TABLE "user_account" ADD CONSTRAINT "user_username_unique" EXCLUDE ("username" WITH =) WHERE ("username" IS NOT NULL AND "deleted_at" IS NULL)',
     );
 
-module.exports.down = knex => knex.schema.dropTable('user_account');
+module.exports.down = (knex) => knex.schema.dropTable('user_account');
diff --git a/server/db/migrations/20180721233450_create_project_table.js b/server/db/migrations/20180721233450_create_project_table.js
index 9e1daa4d..beff276c 100755
--- a/server/db/migrations/20180721233450_create_project_table.js
+++ b/server/db/migrations/20180721233450_create_project_table.js
@@ -1,11 +1,8 @@
-module.exports.up = knex =>
-  knex.schema.createTable('project', table => {
+module.exports.up = (knex) =>
+  knex.schema.createTable('project', (table) => {
     /* Columns */
 
-    table
-      .bigInteger('id')
-      .primary()
-      .defaultTo(knex.raw('next_id()'));
+    table.bigInteger('id').primary().defaultTo(knex.raw('next_id()'));
 
     table.text('name').notNullable();
 
@@ -13,4 +10,4 @@ module.exports.up = knex =>
     table.timestamp('updated_at', true);
   });
 
-module.exports.down = knex => knex.schema.dropTable('project');
+module.exports.down = (knex) => knex.schema.dropTable('project');
diff --git a/server/db/migrations/20180721234154_create_project_membership_table.js b/server/db/migrations/20180721234154_create_project_membership_table.js
index 7a02ef78..23278319 100755
--- a/server/db/migrations/20180721234154_create_project_membership_table.js
+++ b/server/db/migrations/20180721234154_create_project_membership_table.js
@@ -1,11 +1,8 @@
-module.exports.up = knex =>
-  knex.schema.createTable('project_membership', table => {
+module.exports.up = (knex) =>
+  knex.schema.createTable('project_membership', (table) => {
     /* Columns */
 
-    table
-      .bigInteger('id')
-      .primary()
-      .defaultTo(knex.raw('next_id()'));
+    table.bigInteger('id').primary().defaultTo(knex.raw('next_id()'));
 
     table.bigInteger('project_id').notNullable();
     table.bigInteger('user_id').notNullable();
@@ -19,4 +16,4 @@ module.exports.up = knex =>
     table.index('user_id');
   });
 
-module.exports.down = knex => knex.schema.dropTable('project_membership');
+module.exports.down = (knex) => knex.schema.dropTable('project_membership');
diff --git a/server/db/migrations/20180722000627_create_board_table.js b/server/db/migrations/20180722000627_create_board_table.js
index 56204f0e..80342022 100755
--- a/server/db/migrations/20180722000627_create_board_table.js
+++ b/server/db/migrations/20180722000627_create_board_table.js
@@ -1,11 +1,8 @@
-module.exports.up = knex =>
-  knex.schema.createTable('board', table => {
+module.exports.up = (knex) =>
+  knex.schema.createTable('board', (table) => {
     /* Columns */
 
-    table
-      .bigInteger('id')
-      .primary()
-      .defaultTo(knex.raw('next_id()'));
+    table.bigInteger('id').primary().defaultTo(knex.raw('next_id()'));
 
     table.bigInteger('project_id').notNullable();
 
@@ -21,4 +18,4 @@ module.exports.up = knex =>
     table.index('position');
   });
 
-module.exports.down = knex => knex.schema.dropTable('board');
+module.exports.down = (knex) => knex.schema.dropTable('board');
diff --git a/server/db/migrations/20180722003437_create_list_table.js b/server/db/migrations/20180722003437_create_list_table.js
index 3b3edec2..a22c6dd2 100755
--- a/server/db/migrations/20180722003437_create_list_table.js
+++ b/server/db/migrations/20180722003437_create_list_table.js
@@ -1,11 +1,8 @@
-module.exports.up = knex =>
-  knex.schema.createTable('list', table => {
+module.exports.up = (knex) =>
+  knex.schema.createTable('list', (table) => {
     /* Columns */
 
-    table
-      .bigInteger('id')
-      .primary()
-      .defaultTo(knex.raw('next_id()'));
+    table.bigInteger('id').primary().defaultTo(knex.raw('next_id()'));
 
     table.bigInteger('board_id').notNullable();
 
@@ -21,4 +18,4 @@ module.exports.up = knex =>
     table.index('position');
   });
 
-module.exports.down = knex => knex.schema.dropTable('list');
+module.exports.down = (knex) => knex.schema.dropTable('list');
diff --git a/server/db/migrations/20180722003502_create_label_table.js b/server/db/migrations/20180722003502_create_label_table.js
index 77075d46..b2635d8d 100755
--- a/server/db/migrations/20180722003502_create_label_table.js
+++ b/server/db/migrations/20180722003502_create_label_table.js
@@ -1,11 +1,8 @@
-module.exports.up = knex =>
-  knex.schema.createTable('label', table => {
+module.exports.up = (knex) =>
+  knex.schema.createTable('label', (table) => {
     /* Columns */
 
-    table
-      .bigInteger('id')
-      .primary()
-      .defaultTo(knex.raw('next_id()'));
+    table.bigInteger('id').primary().defaultTo(knex.raw('next_id()'));
 
     table.bigInteger('board_id').notNullable();
 
@@ -20,4 +17,4 @@ module.exports.up = knex =>
     table.index('board_id');
   });
 
-module.exports.down = knex => knex.schema.dropTable('label');
+module.exports.down = (knex) => knex.schema.dropTable('label');
diff --git a/server/db/migrations/20180722003614_create_card_table.js b/server/db/migrations/20180722003614_create_card_table.js
index 4b502252..b9085ca1 100755
--- a/server/db/migrations/20180722003614_create_card_table.js
+++ b/server/db/migrations/20180722003614_create_card_table.js
@@ -1,11 +1,8 @@
-module.exports.up = knex =>
-  knex.schema.createTable('card', table => {
+module.exports.up = (knex) =>
+  knex.schema.createTable('card', (table) => {
     /* Columns */
 
-    table
-      .bigInteger('id')
-      .primary()
-      .defaultTo(knex.raw('next_id()'));
+    table.bigInteger('id').primary().defaultTo(knex.raw('next_id()'));
 
     table.bigInteger('list_id').notNullable();
     table.bigInteger('board_id').notNullable();
@@ -25,4 +22,4 @@ module.exports.up = knex =>
     table.index('position');
   });
 
-module.exports.down = knex => knex.schema.dropTable('card');
+module.exports.down = (knex) => knex.schema.dropTable('card');
diff --git a/server/db/migrations/20180722005122_create_card_subscription_table.js b/server/db/migrations/20180722005122_create_card_subscription_table.js
index 83988698..b01266ab 100755
--- a/server/db/migrations/20180722005122_create_card_subscription_table.js
+++ b/server/db/migrations/20180722005122_create_card_subscription_table.js
@@ -1,11 +1,8 @@
-module.exports.up = knex =>
-  knex.schema.createTable('card_subscription', table => {
+module.exports.up = (knex) =>
+  knex.schema.createTable('card_subscription', (table) => {
     /* Columns */
 
-    table
-      .bigInteger('id')
-      .primary()
-      .defaultTo(knex.raw('next_id()'));
+    table.bigInteger('id').primary().defaultTo(knex.raw('next_id()'));
 
     table.bigInteger('card_id').notNullable();
     table.bigInteger('user_id').notNullable();
@@ -21,4 +18,4 @@ module.exports.up = knex =>
     table.index('user_id');
   });
 
-module.exports.down = knex => knex.schema.dropTable('card_subscription');
+module.exports.down = (knex) => knex.schema.dropTable('card_subscription');
diff --git a/server/db/migrations/20180722005359_create_card_membership_table.js b/server/db/migrations/20180722005359_create_card_membership_table.js
index ce720d4a..85d2e96b 100755
--- a/server/db/migrations/20180722005359_create_card_membership_table.js
+++ b/server/db/migrations/20180722005359_create_card_membership_table.js
@@ -1,11 +1,8 @@
-module.exports.up = knex =>
-  knex.schema.createTable('card_membership', table => {
+module.exports.up = (knex) =>
+  knex.schema.createTable('card_membership', (table) => {
     /* Columns */
 
-    table
-      .bigInteger('id')
-      .primary()
-      .defaultTo(knex.raw('next_id()'));
+    table.bigInteger('id').primary().defaultTo(knex.raw('next_id()'));
 
     table.bigInteger('card_id').notNullable();
     table.bigInteger('user_id').notNullable();
@@ -19,4 +16,4 @@ module.exports.up = knex =>
     table.index('user_id');
   });
 
-module.exports.down = knex => knex.schema.dropTable('card_membership');
+module.exports.down = (knex) => knex.schema.dropTable('card_membership');
diff --git a/server/db/migrations/20180722005928_create_card_label_table.js b/server/db/migrations/20180722005928_create_card_label_table.js
index 02eeaccb..1d9fb792 100755
--- a/server/db/migrations/20180722005928_create_card_label_table.js
+++ b/server/db/migrations/20180722005928_create_card_label_table.js
@@ -1,11 +1,8 @@
-module.exports.up = knex =>
-  knex.schema.createTable('card_label', table => {
+module.exports.up = (knex) =>
+  knex.schema.createTable('card_label', (table) => {
     /* Columns */
 
-    table
-      .bigInteger('id')
-      .primary()
-      .defaultTo(knex.raw('next_id()'));
+    table.bigInteger('id').primary().defaultTo(knex.raw('next_id()'));
 
     table.bigInteger('card_id').notNullable();
     table.bigInteger('label_id').notNullable();
@@ -19,4 +16,4 @@ module.exports.up = knex =>
     table.index('label_id');
   });
 
-module.exports.down = knex => knex.schema.dropTable('card_label');
+module.exports.down = (knex) => knex.schema.dropTable('card_label');
diff --git a/server/db/migrations/20180722006570_create_task_table.js b/server/db/migrations/20180722006570_create_task_table.js
index ead0beda..ed04b04a 100755
--- a/server/db/migrations/20180722006570_create_task_table.js
+++ b/server/db/migrations/20180722006570_create_task_table.js
@@ -1,11 +1,8 @@
-module.exports.up = knex =>
-  knex.schema.createTable('task', table => {
+module.exports.up = (knex) =>
+  knex.schema.createTable('task', (table) => {
     /* Columns */
 
-    table
-      .bigInteger('id')
-      .primary()
-      .defaultTo(knex.raw('next_id()'));
+    table.bigInteger('id').primary().defaultTo(knex.raw('next_id()'));
 
     table.bigInteger('card_id').notNullable();
 
@@ -20,4 +17,4 @@ module.exports.up = knex =>
     table.index('card_id');
   });
 
-module.exports.down = knex => knex.schema.dropTable('task');
+module.exports.down = (knex) => knex.schema.dropTable('task');
diff --git a/server/db/migrations/20181024220134_create_action_table.js b/server/db/migrations/20181024220134_create_action_table.js
index cd067682..b7861067 100755
--- a/server/db/migrations/20181024220134_create_action_table.js
+++ b/server/db/migrations/20181024220134_create_action_table.js
@@ -1,11 +1,8 @@
-module.exports.up = knex =>
-  knex.schema.createTable('action', table => {
+module.exports.up = (knex) =>
+  knex.schema.createTable('action', (table) => {
     /* Columns */
 
-    table
-      .bigInteger('id')
-      .primary()
-      .defaultTo(knex.raw('next_id()'));
+    table.bigInteger('id').primary().defaultTo(knex.raw('next_id()'));
 
     table.bigInteger('card_id').notNullable();
     table.bigInteger('user_id').notNullable();
@@ -21,4 +18,4 @@ module.exports.up = knex =>
     table.index('card_id');
   });
 
-module.exports.down = knex => knex.schema.dropTable('action');
+module.exports.down = (knex) => knex.schema.dropTable('action');
diff --git a/server/db/migrations/20181112104653_create_notification_table.js b/server/db/migrations/20181112104653_create_notification_table.js
index c5b3759d..77dfdf52 100755
--- a/server/db/migrations/20181112104653_create_notification_table.js
+++ b/server/db/migrations/20181112104653_create_notification_table.js
@@ -1,11 +1,8 @@
-module.exports.up = knex =>
-  knex.schema.createTable('notification', table => {
+module.exports.up = (knex) =>
+  knex.schema.createTable('notification', (table) => {
     /* Columns */
 
-    table
-      .bigInteger('id')
-      .primary()
-      .defaultTo(knex.raw('next_id()'));
+    table.bigInteger('id').primary().defaultTo(knex.raw('next_id()'));
 
     table.bigInteger('user_id').notNullable();
     table.bigInteger('action_id').notNullable();
@@ -24,4 +21,4 @@ module.exports.up = knex =>
     table.index('is_read');
   });
 
-module.exports.down = knex => knex.schema.dropTable('notification');
+module.exports.down = (knex) => knex.schema.dropTable('notification');
diff --git a/server/db/seeds/default.js b/server/db/seeds/default.js
index 967a900e..14d89750 100644
--- a/server/db/seeds/default.js
+++ b/server/db/seeds/default.js
@@ -1,6 +1,6 @@
 const bcrypt = require('bcrypt');
 
-exports.seed = knex => {
+exports.seed = (knex) => {
   const date = new Date().toUTCString();
 
   return knex('user_account').insert({
@@ -8,6 +8,7 @@ exports.seed = knex => {
     password: bcrypt.hashSync('demo', 10),
     isAdmin: true,
     name: 'Demo Demo',
+    username: 'demo',
     createdAt: date,
     updatedAt: date,
   });
diff --git a/server/package-lock.json b/server/package-lock.json
index 1038ecba..06157ed3 100644
--- a/server/package-lock.json
+++ b/server/package-lock.json
@@ -90,6 +90,13 @@
       "requires": {
         "@sailshq/lodash": "^3.10.2",
         "validator": "5.7.0"
+      },
+      "dependencies": {
+        "validator": {
+          "version": "5.7.0",
+          "resolved": "https://registry.npmjs.org/validator/-/validator-5.7.0.tgz",
+          "integrity": "sha1-eoelgUa2laxIYHEUHAxJ1n2gXlw="
+        }
       }
     },
     "ansi-align": {
@@ -6791,9 +6798,9 @@
       }
     },
     "validator": {
-      "version": "5.7.0",
-      "resolved": "https://registry.npmjs.org/validator/-/validator-5.7.0.tgz",
-      "integrity": "sha1-eoelgUa2laxIYHEUHAxJ1n2gXlw="
+      "version": "13.0.0",
+      "resolved": "https://registry.npmjs.org/validator/-/validator-13.0.0.tgz",
+      "integrity": "sha512-anYx5fURbgF04lQV18nEQWZ/3wHGnxiKdG4aL8J+jEDsm98n/sU/bey+tYk6tnGJzm7ioh5FoqrAiQ6m03IgaA=="
     },
     "vary": {
       "version": "1.1.2",
diff --git a/server/package.json b/server/package.json
index e40e9768..813aad10 100644
--- a/server/package.json
+++ b/server/package.json
@@ -51,7 +51,8 @@
     "sails-hook-sockets": "^2.0.0",
     "sails-postgresql": "^1.0.2",
     "sharp": "^0.25.2",
-    "uuid": "^7.0.2"
+    "uuid": "^7.0.2",
+    "validator": "^13.0.0"
   },
   "devDependencies": {
     "eslint": "^6.8.0",