What is a Chrome Extension Manifest V3?

Manifest V3 is the latest version of the Chrome extension platform specification. It replaced Manifest V2 as of 2023 and introduces a service worker for background tasks instead of persistent background pages, stricter permissions, and improved security. All new Chrome extensions must use Manifest V3.

Is this tool free to use?

Yes, completely free. The manifest is generated 100% in your browser — no data is sent to any server, and no sign-up is required.

What permissions should I include in my Chrome extension?

Only request the permissions your extension actually needs — Chrome may warn users about sensitive permissions during installation. Common safe permissions include 'storage', 'tabs', 'activeTab', and 'scripting'. Avoid broad host permissions like ' ' unless absolutely necessary.

What is the difference between permissions and host permissions?

Permissions grant access to Chrome APIs (e.g., 'storage', 'tabs', 'notifications'). Host permissions grant access to specific websites or URL patterns (e.g., 'https://*.example.com/*'). Both are required fields in Manifest V3 when your extension interacts with web pages or Chrome APIs.

Can I use this manifest with Firefox or Edge extensions?

The generated manifest follows the Chrome Manifest V3 specification. Firefox and Edge support WebExtensions, which overlap significantly with Chrome's format. Firefox has partial Manifest V3 support, so you may need minor tweaks for cross-browser compatibility.

What is a service worker in a Chrome extension?

In Manifest V3, the background service worker replaces the persistent background page from Manifest V2. It runs in the background to handle events (e.g., browser action clicks, alarms, messages) but is terminated when idle to save resources. Specify its filename in the 'background.service_worker' field.

Chrome Extension Tool

Generate Your Chrome Extension
Manifest V3 JSON

Select permissions, configure content scripts, and set up a service worker. Get a valid manifest.json in seconds — 100% client-side, no sign-up needed.

🔑

Permission Picker

Browse 30+ Chrome APIs and host permissions. Check what you need and the manifest updates live.

📜

Content Scripts

Set URL match patterns, inject JS/CSS files, and choose when scripts run — at document start, end, or idle.

⚙️

Action & Service Worker

Configure your extension popup, default title, toolbar icon, and background service worker in one place.

📝 Basic Info

Extension Name

Version

Description

Include icon paths (icons/icon16.png, etc.)

🔑 Permissions

Host Permissions (one per line)

🖱️ Action (Toolbar Button)

Popup HTML

Leave blank to omit the popup

Default Title

⚙️ Background Service Worker

Service Worker Script

Leave blank to omit the background section

Module Type

📜 Content Scripts

No content scripts added. Click "Add Script" to inject JS/CSS into pages.

🔧 Options Page (optional)

Options Page HTML

manifest.jsonManifest V3

{
  "manifest_version": 3,
  "name": "My Extension",
  "version": "1.0.0",
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon16.png",
      "48": "icons/icon48.png"
    }
  },
  "background": {
    "service_worker": "background.js",
    "type": "module"
  }
}

💡 Quick Guide

Save the output as manifest.json at the root of your extension folder
Use activeTab instead of broad host permissions where possible
Test with chrome://extensions → Developer mode → Load unpacked
Only module type service workers support ES module imports

Frequently Asked Questions

Everything you need to know about Chrome Extension Manifest Generator.

Generate Your Chrome ExtensionManifest V3 JSON