diff --git a/src/tools/epoch-converter/epoch-converter.e2e.spec.ts b/src/tools/epoch-converter/epoch-converter.e2e.spec.ts
index d393e8e2..ebc4ca34 100644
--- a/src/tools/epoch-converter/epoch-converter.e2e.spec.ts
+++ b/src/tools/epoch-converter/epoch-converter.e2e.spec.ts
@@ -13,7 +13,8 @@ test.describe('Tool - Epoch converter', () => {
     await page.getByPlaceholder('Enter epoch timestamp').fill('1750452480');
     await page.getByRole('button', { name: 'Convert to Date' }).click();
 
-    await expect(page.getByText('6/23/2025, 12:31:00 PM')).toBeVisible();
+    await expect(page.getByText('GMT (UTC): Fri, 20 Jun 2025 20:48:00 GMT')).toBeVisible();
+    await expect(page.getByText('Local Time: Fri, 20 Jun 2025, 13:48:00 GMT-7')).toBeVisible();
   });
 
   test('Converts known date to epoch timestamp', async ({ page }) => {
@@ -28,4 +29,40 @@ test.describe('Tool - Epoch converter', () => {
 
     await expect(page.getByText('1750452480')).toBeVisible();
   });
+
+  test('Shows error if year is not 4 digits', async ({ page }) => {
+    await page.getByPlaceholder('YYYY').fill('99');
+    await page.getByRole('button', { name: 'Convert to Epoch (Local)' }).click();
+    await expect(page.getByText('Year must be 4 digits')).toBeVisible();
+  });
+
+  test('Shows error if month is invalid', async ({ page }) => {
+    await page.getByPlaceholder('MM').first().fill('00');
+    await page.getByRole('button', { name: 'Convert to Epoch (Local)' }).click();
+    await expect(page.getByText('Month must be between 1 and 12')).toBeVisible();
+  });
+
+  test('Shows error if day is invalid', async ({ page }) => {
+    await page.getByPlaceholder('DD').fill('0');
+    await page.getByRole('button', { name: 'Convert to Epoch (UTC)' }).click();
+    await expect(page.getByText('Day must be between 1 and 31')).toBeVisible();
+  });
+
+  test('Shows error if hour is invalid', async ({ page }) => {
+    await page.getByPlaceholder('HH').fill('24');
+    await page.getByRole('button', { name: 'Convert to Epoch (Local)' }).click();
+    await expect(page.getByText('Hour must be between 0 and 23')).toBeVisible();
+  });
+
+  test('Shows error if minute is invalid', async ({ page }) => {
+    await page.getByPlaceholder('MM').nth(1).fill('61');
+    await page.getByRole('button', { name: 'Convert to Epoch (UTC)' }).click();
+    await expect(page.getByText('Minute must be between 0 and 59')).toBeVisible();
+  });
+
+  test('Shows error if second is invalid', async ({ page }) => {
+    await page.getByPlaceholder('SS').fill('99');
+    await page.getByRole('button', { name: 'Convert to Epoch (UTC)' }).click();
+    await expect(page.getByText('Second must be between 0 and 59')).toBeVisible();
+  });
 });
diff --git a/src/tools/epoch-converter/epoch-converter.service.test.ts b/src/tools/epoch-converter/epoch-converter.service.test.ts
index 8fdd31ba..b841fa3b 100644
--- a/src/tools/epoch-converter/epoch-converter.service.test.ts
+++ b/src/tools/epoch-converter/epoch-converter.service.test.ts
@@ -1,12 +1,22 @@
+import process from 'node:process';
 import { describe, expect, it } from 'vitest';
-import { dateToEpoch, epochToDate } from './epoch-converter.service';
+import { type DateParts, dateToEpoch, epochToDate, getISODateString } from './epoch-converter.service';
+
+process.env.TZ = 'America/Vancouver';
 
 describe('epochToDate', () => {
-  it('converts known epoch seconds to correct local date string', () => {
+  it('converts known epoch seconds to correct formatted date (America/Vancouver)', () => {
     const epoch = 1750707060;
-    const expectedDate = '6/23/2025, 12:31:00 PM';
-    const result = epochToDate(epoch);
-    expect(result).toBe(expectedDate);
+    const expectedUTC = 'Mon, 23 Jun 2025 19:31:00 GMT';
+    const expectedLocal = 'Mon, Jun 23, 2025, 12:31:00 PDT';
+
+    const result = epochToDate(epoch, {
+      timeZone: 'America/Vancouver',
+      locale: 'en-US',
+    });
+
+    expect(result.local).toBe(expectedLocal);
+    expect(result.utc).toBe(expectedUTC);
   });
 
   it('throws for invalid string input', () => {
@@ -19,13 +29,21 @@ describe('epochToDate', () => {
 });
 
 describe('dateToEpoch', () => {
-  it('converts a known date to correct epoch (2025-06-20 13:48:00)', () => {
+  it('converts a known local date to correct epoch (2025-06-20 13:48:00)', () => {
     const input = '2025-06-20T13:48:00';
+
     const expectedEpoch = 1750452480;
     const result = dateToEpoch(input);
     expect(result).toBe(expectedEpoch);
   });
 
+  it('converts a UTC date to correct epoch', () => {
+    const input = '2025-06-20T13:48:00';
+    const expectedEpoch = 1750427280;
+    const result = dateToEpoch(input, { parseAsUTC: true });
+    expect(result).toBe(expectedEpoch);
+  });
+
   it('throws for invalid date string', () => {
     expect(() => dateToEpoch('not-a-date')).toThrowError(TypeError);
   });
@@ -34,3 +52,93 @@ describe('dateToEpoch', () => {
     expect(() => dateToEpoch('')).toThrowError(TypeError);
   });
 });
+
+describe('epochToDate - Year 2038 boundary', () => {
+  it('converts max 32-bit signed int epoch correctly (2038-01-19 03:14:07)', () => {
+    const epoch = 2147483647;
+
+    const result = epochToDate(epoch, {
+      timeZone: 'America/Vancouver',
+      locale: 'en-US',
+    });
+
+    const expectedLocal = 'Mon, Jan 18, 2038, 19:14:07 PST';
+
+    const expectedUTC = 'Tue, 19 Jan 2038 03:14:07 GMT';
+
+    expect(result.local).toBe(expectedLocal);
+    expect(result.utc).toBe(expectedUTC);
+  });
+
+  it('handles epoch just after 32-bit boundary (2038-01-19 03:14:08)', () => {
+    const epoch = 2147483648;
+
+    const result = epochToDate(epoch, {
+      timeZone: 'America/Vancouver',
+      locale: 'en-US',
+    });
+
+    const expectedLocal = 'Mon, Jan 18, 2038, 19:14:08 PST';
+
+    const expectedUTC = 'Tue, 19 Jan 2038 03:14:08 GMT';
+
+    expect(result.local).toBe(expectedLocal);
+    expect(result.utc).toBe(expectedUTC);
+  });
+});
+
+describe('dateToEpoch - Year 2038 boundary (UTC)', () => {
+  it('converts "2038-01-19T03:14:07" to epoch 2147483647 in UTC mode', () => {
+    const result = dateToEpoch('2038-01-19T03:14:07', { parseAsUTC: true });
+    expect(result).toBe(2147483647);
+  });
+
+  it('converts "2038-01-19T03:14:08" to epoch 2147483648 in UTC mode', () => {
+    const result = dateToEpoch('2038-01-19T03:14:08', { parseAsUTC: true });
+    expect(result).toBe(2147483648);
+  });
+});
+
+describe('getISODateString', () => {
+  it('generates a correctly padded ISO date string from date parts', () => {
+    const parts: DateParts = {
+      year: '2025',
+      month: '6',
+      day: '3',
+      hour: '9',
+      minute: '5',
+      second: '1',
+    };
+
+    const isoString = getISODateString(parts);
+    expect(isoString).toBe('2025-06-03T09:05:01');
+  });
+
+  it('handles already padded inputs correctly', () => {
+    const parts: DateParts = {
+      year: '2025',
+      month: '12',
+      day: '31',
+      hour: '23',
+      minute: '59',
+      second: '59',
+    };
+
+    const isoString = getISODateString(parts);
+    expect(isoString).toBe('2025-12-31T23:59:59');
+  });
+
+  it('handles all-zero input values', () => {
+    const parts: DateParts = {
+      year: '2025',
+      month: '0',
+      day: '0',
+      hour: '0',
+      minute: '0',
+      second: '0',
+    };
+
+    const isoString = getISODateString(parts);
+    expect(isoString).toBe('2025-00-00T00:00:00');
+  });
+});
diff --git a/src/tools/epoch-converter/epoch-converter.service.ts b/src/tools/epoch-converter/epoch-converter.service.ts
index 3f527f86..ee12bf68 100644
--- a/src/tools/epoch-converter/epoch-converter.service.ts
+++ b/src/tools/epoch-converter/epoch-converter.service.ts
@@ -1,19 +1,76 @@
-// Convert Epoch to Human Readable Date
-export function epochToDate(epoch: string | number): string {
+const MILLISECONDS_THRESHOLD = 1_000_000_000_000;
+const MILLISECONDS_IN_SECOND = 1000;
+
+export interface DateParts {
+  year: string
+  month: string
+  day: string
+  hour: string
+  minute: string
+  second: string
+}
+
+/**
+ * Converts a Unix epoch timestamp (in seconds or milliseconds) to a human-readable date.
+ *
+ * @param epoch - The epoch timestamp to convert (number or string).
+ * @param options - Optional locale and timeZone settings for local time formatting.
+ * @returns An object with both the local formatted string and UTC string.
+ */
+export function epochToDate(
+  epoch: string | number,
+  options?: { timeZone?: string; locale?: string },
+): { local: string; utc: string } {
   const num = typeof epoch === 'string' ? Number.parseInt(epoch, 10) : epoch;
 
   if (Number.isNaN(num)) {
     throw new TypeError('Invalid epoch timestamp');
   }
 
-  const timestamp = num < 1e12 ? num * 1000 : num;
+  const isSecondsPrecision = num < MILLISECONDS_THRESHOLD;
+  const timestampInMs = isSecondsPrecision
+    ? num * MILLISECONDS_IN_SECOND
+    : num;
 
-  return new Date(timestamp).toLocaleString();
+  const date = new Date(timestampInMs);
+
+  const local = date.toLocaleString(options?.locale || 'en-US', {
+    timeZone: options?.timeZone,
+    weekday: 'short',
+    year: 'numeric',
+    month: 'short',
+    day: '2-digit',
+    hour: '2-digit',
+    minute: '2-digit',
+    second: '2-digit',
+    hour12: false,
+    timeZoneName: 'short',
+  });
+
+  const utc = date.toUTCString();
+
+  return { local, utc };
 }
 
-// Convert Human Readable Date to Epoch
-export function dateToEpoch(dateString: string): number {
-  const date = new Date(dateString);
+/**
+ * Converts a human-readable ISO date string into a Unix epoch timestamp (in seconds).
+ *
+ * @param dateString - A string in ISO format (e.g. "2025-06-20T13:48:00").
+ * @param options - Optional flag to interpret the date string as UTC time.
+ * @returns Epoch time as a number in seconds.
+ */
+export function dateToEpoch(
+  dateString: string,
+  options?: {
+    parseAsUTC?: boolean // if true, the date string will be parsed as UTC
+  },
+): number {
+  const shouldNormalizeToUTC = options?.parseAsUTC === true && !dateString.endsWith('Z');
+  const normalizedDateString = shouldNormalizeToUTC
+    ? `${dateString}Z`
+    : dateString;
+
+  const date = new Date(normalizedDateString);
 
   if (Number.isNaN(date.getTime())) {
     throw new TypeError('Invalid date string');
@@ -21,3 +78,22 @@ export function dateToEpoch(dateString: string): number {
 
   return Math.floor(date.getTime() / 1000);
 }
+
+/**
+ * Creates an ISO 8601 date string (e.g., "2025-06-20T13:48:00") from date parts.
+ * Ensures all components are zero-padded to 2 digits.
+ *
+ * @param parts - An object containing the year, month, day, hour, minute, and second.
+ * @returns A valid ISO string.
+ */
+export function getISODateString({
+  year,
+  month,
+  day,
+  hour,
+  minute,
+  second,
+}: DateParts): string {
+  const pad = (value: string) => value.toString().padStart(2, '0');
+  return `${year}-${pad(month)}-${pad(day)}T${pad(hour)}:${pad(minute)}:${pad(second)}`;
+}
diff --git a/src/tools/epoch-converter/epoch-converter.vue b/src/tools/epoch-converter/epoch-converter.vue
index aaaa5abd..0d6c7364 100644
--- a/src/tools/epoch-converter/epoch-converter.vue
+++ b/src/tools/epoch-converter/epoch-converter.vue
@@ -1,13 +1,16 @@
 <script setup lang="ts">
 import { ref } from 'vue';
-import { dateToEpoch, epochToDate } from './epoch-converter.service.ts';
+import { type DateParts, dateToEpoch, epochToDate, getISODateString } from './epoch-converter.service.ts';
 
 const epochInput = ref('');
-const dateOutput = ref('');
+const dateOutput = ref<{ local: string; utc: string } | null>(null);
 const epochOutput = ref('');
 const error = ref<string | null>(null);
 
-const dateParts = ref({
+const epochInputError = ref<string | null>(null);
+const dateInputError = ref<string | null>(null);
+
+const dateParts = ref<DateParts>({
   year: '',
   month: '',
   day: '',
@@ -16,32 +19,84 @@ const dateParts = ref({
   second: '',
 });
 
+/**
+ * Converts a Unix epoch timestamp to human-readable date strings
+ * Accepts seconds (10-digit) or milliseconds (13-digit)
+ */
 function convertEpochToDate() {
   error.value = null;
   try {
     dateOutput.value = epochToDate(epochInput.value);
   }
   catch (e: any) {
-    error.value = e.message;
+    epochInputError.value = e.message;
   }
 }
 
-function convertDateToEpoch() {
-  error.value = null;
+/**
+ * Converts a Unix epoch timestamp to human-readable date strings
+ * Accepts seconds (10-digit) or milliseconds (13-digit)
+ */
+function convertDateToEpochLocal() {
   try {
-    const { year, month, day, hour, minute, second } = dateParts.value;
-
-    const isoString = `${year}-${pad(month)}-${pad(day)}T${pad(hour)}:${pad(minute)}:${pad(second)}`;
+    validateDateParts(dateParts.value);
+    const isoString = getISODateString(dateParts.value);
     epochOutput.value = dateToEpoch(isoString);
+    dateInputError.value = null;
   }
   catch (e: any) {
-    error.value = e.message;
+    epochOutput.value = '';
+    dateInputError.value = e.message;
   }
 }
 
-function pad(value: string): string {
-  return value.toString().padStart(2, '0');
+/**
+ * Converts UTC date string parts to epoch (seconds)
+ */
+function convertDateToEpochUTC() {
+  try {
+    validateDateParts(dateParts.value);
+    const isoString = getISODateString(dateParts.value);
+    epochOutput.value = dateToEpoch(isoString, { utc: true });
+    dateInputError.value = null;
+  }
+  catch (e: any) {
+    epochOutput.value = '';
+    dateInputError.value = e.message;
+  }
 }
+
+function validateDateParts(parts: DateParts): void {
+  const { year, month, day, hour, minute, second } = parts;
+
+  if (!/^\d{4}$/.test(year)) {
+    throw new Error('Year must be 4 digits');
+  }
+  if (+month < 1 || +month > 12) {
+    throw new Error('Month must be between 1 and 12');
+  }
+  if (+day < 1 || +day > 31) {
+    throw new Error('Day must be between 1 and 31');
+  }
+  if (+hour < 0 || +hour > 23) {
+    throw new Error('Hour must be between 0 and 23');
+  }
+  if (+minute < 0 || +minute > 59) {
+    throw new Error('Minute must be between 0 and 59');
+  }
+  if (+second < 0 || +second > 59) {
+    throw new Error('Second must be between 0 and 59');
+  }
+}
+
+// Clear errors on input
+watch(epochInput, () => {
+  epochInputError.value = null;
+});
+
+watch(dateParts, () => {
+  dateInputError.value = null;
+}, { deep: true });
 </script>
 
 <template>
@@ -51,6 +106,16 @@ function pad(value: string): string {
       <div class="mb-2 font-semibold">
         Epoch to Date
       </div>
+
+      <div class="mb-2 text-xs text-neutral-400">
+        Epoch is interpreted as:
+        <ul class="mt-1 list-disc pl-4">
+          <li><strong>10 digits</strong> → seconds (e.g. <code>1718822594</code>)</li>
+          <li><strong>13 digits</strong> → milliseconds (e.g. <code>1718822594000</code>)</li>
+        </ul>
+        Epoch values outside supported JavaScript range (±8.64e15) may result in invalid dates.
+      </div>
+
       <c-input-text
         v-model:value="epochInput"
         placeholder="Enter epoch timestamp (e.g. 1718822594)"
@@ -61,11 +126,16 @@ function pad(value: string): string {
         Convert to Date
       </c-button>
 
-      <div v-if="dateOutput" class="mt-4 text-sm text-green-400">
-        Human-Readable Date: <strong>{{ dateOutput }}</strong>
+      <div v-if="dateOutput" class="mt-4 text-sm text-green-400 space-y-1">
+        <div>Local Time: <strong>{{ dateOutput.local }}</strong></div>
+        <div>GMT (UTC): <strong>{{ dateOutput.utc }}</strong></div>
       </div>
     </div>
 
+    <c-alert v-if="epochInputError" type="error" class="mb-4 mt-4">
+      {{ epochInputError }}
+    </c-alert>
+
     <!-- Date to Epoch -->
     <div class="mb-8">
       <div class="mb-2 font-semibold">
@@ -99,17 +169,22 @@ function pad(value: string): string {
         </div>
       </div>
 
-      <c-button @click="convertDateToEpoch">
-        Convert to Epoch
-      </c-button>
+      <div class="mt-2 flex gap-4">
+        <c-button @click="convertDateToEpochLocal">
+          Convert to Epoch (Local)
+        </c-button>
+        <c-button @click="convertDateToEpochUTC">
+          Convert to Epoch (UTC)
+        </c-button>
+      </div>
 
       <div v-if="epochOutput" class="mt-4 text-sm text-green-400">
         Epoch Timestamp: <strong>{{ epochOutput }}</strong>
       </div>
     </div>
 
-    <c-alert v-if="error" type="error" class="mt-6">
-      {{ error }}
+    <c-alert v-if="dateInputError" type="error" class="mb-4 mt-4">
+      {{ dateInputError }}
     </c-alert>
   </c-card>
 </template>
diff --git a/src/tools/index.ts b/src/tools/index.ts
index 67a1e6f6..d38359d5 100644
--- a/src/tools/index.ts
+++ b/src/tools/index.ts
@@ -1,6 +1,7 @@
 import { tool as base64FileConverter } from './base64-file-converter';
 import { tool as base64StringConverter } from './base64-string-converter';
 import { tool as basicAuthGenerator } from './basic-auth-generator';
+import { tool as gzipDecompressor } from './gzip-decompressor';
 import { tool as epochConverter } from './epoch-converter';
 import { tool as emailNormalizer } from './email-normalizer';