A curated list of the best tools, frameworks, libraries, and resources for building modern browser extensions (Chrome, Edge, Firefox, Safari) in 2026. Covers Manifest V3, cross-browser development with WXT and Plasmo, build tooling, testing, publishing automation, security, and growth.
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- Official Documentation
- Frameworks and Boilerplates
- Manifest V3 and Migration
- Cross-Browser and Polyfills
- UI and Components
- Messaging and Storage
- Build Tools and Bundlers
- Testing and Debugging
- Publishing and Store Automation
- Analytics and Monetization
- Growth and Store Optimization
- Security and Privacy
- Example Open-Source Extensions
- Communities and Newsletters
- AI in Extensions
- Tools and Utilities
The primary references maintained by browser vendors and standards bodies.
- Chrome Extensions (Chrome for Developers) - The definitive reference for Chrome extension APIs, manifest keys, permissions, and Manifest V3 architecture.
- Chrome Extensions API Reference - Full API surface for all Chrome extension namespaces, with live examples and changelog.
- Chrome Web Store Developer Docs - Publishing guidelines, listing policies, review processes, and monetization options for the Chrome Web Store.
- What's New in Chrome Extensions - Official changelog tracking new APIs, deprecations, and platform changes across Chrome versions.
- MDN WebExtensions (Firefox) - Cross-browser WebExtensions API reference covering Firefox, Chrome, and Edge with compatibility tables.
- Firefox Extension Workshop - Mozilla's guide for building, testing, and publishing Firefox add-ons, including Firefox-specific capabilities.
- Microsoft Edge Extensions Docs - Microsoft Learn documentation covering Edge extension development, publishing to the Edge Add-ons store, and MV3 guidance.
- Safari Web Extensions (Apple Developer) - Apple's guide for building Safari extensions using the WebExtensions API, with Xcode packaging instructions.
- Safari Extensions Overview (Apple) - Landing page for all Safari extension types including web extensions, app extensions, and content blockers.
Purpose-built frameworks and starter templates that reduce extension setup time.
- WXT - Next-generation browser extension framework with HMR, auto-reloading, TypeScript-first design, and support for all major UI frameworks.
- WXT GitHub - Source repository for WXT, with 7,000+ stars and active community on Discord.
- Plasmo - Battery-packed browser extension SDK with React/Vue/Svelte support, live reload, and built-in publishing workflows.
- Plasmo GitHub - Source repository for the Plasmo framework, including BPP (Browser Platform Publish) GitHub Action.
- CRXJS Vite Plugin - Vite plugin for Chrome/browser extensions with true HMR in content scripts, zero-config manifest handling, and MV3 support.
- CRXJS GitHub - Source for the
@crxjs/vite-pluginpackage and chrome-extension-tools monorepo. - Extension.js - Zero-config, framework-agnostic browser extension framework with HMR for all extension contexts and first-class TypeScript support.
- Extension.js GitHub - Open-source MIT-licensed repository for Extension.js with React, Vue, Svelte, and Preact templates.
- vite-plugin-web-extension - Vite plugin that auto-builds all inputs from manifest.json and opens a browser for development with HMR.
- vitesse-webext - Opinionated WebExtension starter built on Vite and Vue 3, by Anthony Fu, with webext-bridge messaging and VueUse storage.
- chrome-extension-boilerplate-react-vite - Chrome and Firefox extension boilerplate using React, Vite, TypeScript, and Turborepo for fast multi-package builds.
- web-extension-starter - "Write once, run on any browser" extension starter with React, TypeScript, Vite, and cross-browser manifest generation.
- browser-extension-template - Minimal boilerplate with Parcel 2, webext-options-sync, and auto-publishing by fregante.
Resources for understanding MV3 architecture and migrating from MV2.
- What is Manifest V3? (Chrome) - Official overview of MV3 goals, key changes (service workers, declarativeNetRequest, CSP), and platform vision.
- Migrate to Manifest V3 (Chrome) - Step-by-step migration guide covering background script changes, API substitutions, and manifest key updates.
- MV3 Migration (Microsoft Edge) - Edge-specific MV3 overview and migration timeline mirroring Chrome's transition.
- Resuming the Transition to MV3 (Chrome Blog) - Official blog post on MV2 deprecation timelines, including the June 2024 Chrome 127 enforcement rollout.
- declarativeNetRequest API Reference - Full reference for the MV3 network-request filtering API that replaces the blocking webRequest API.
- MV3 Migration Pitfalls (DEV Community) - Practical lessons from migrating 17 real extensions, covering service worker lifecycle, storage, and messaging edge cases.
- Extension Booster MV2 to V3 Auto-Converter - Automated tool that converts Manifest V2 extensions to V3 format, available as part of the Extension Booster platform.
Libraries and resources for writing extensions that work across Chrome, Firefox, Edge, and Safari.
- webextension-polyfill (Mozilla) - Lightweight Promise-based polyfill for the browser WebExtension API, enabling Firefox-style
browser.*calls to work in Chrome. - Build a Cross-Browser Extension (MDN) - MDN guide covering strategy, namespace handling, API gaps, and testing across browsers.
- webextension-toolbox - Small CLI toolbox that compiles and validates extensions targeting Chrome, Firefox, Edge, and Safari from a single codebase.
- Browser Compatibility (Firefox Extension Workshop) - Firefox's reference for which WebExtension APIs are supported across browsers, with notes on Firefox-specific capabilities.
- webextension-polyfill-ts - TypeScript-ready wrapper around Mozilla's webextension-polyfill with full type definitions.
Frameworks, patterns, and libraries for building popup, options, side panel, and content-script UIs.
- shadcn/ui in Extensions (Extension.js docs) - Guide for using shadcn/ui components inside browser extensions with Tailwind CSS and proper content-script isolation.
- WXT Content Scripts UI Guide - WXT documentation on injecting isolated UI into host pages using Shadow DOM to prevent style conflicts.
- Headless UI - Completely unstyled, accessible UI components for React and Vue, well-suited for extension popups and options pages.
- Radix UI - Low-level, accessible UI primitives for React, used as the foundation for shadcn/ui and easy to adapt for extension contexts.
- wxt-react-shadcn-tailwindcss-chrome-extension - Reference boilerplate combining WXT, React, shadcn/ui, and Tailwind CSS with proper Shadow DOM isolation for content scripts.
- vite-web-extension (JohnBra) - Chrome and Firefox extension template using React 19, TypeScript, and Tailwind CSS with a focus on developer ergonomics.
Libraries for type-safe cross-context communication and storage in extensions.
- webext-bridge - Messaging library with batteries included for sending type-safe messages between background, content scripts, popup, devtools, and options pages.
- @webext-core/messaging - Lightweight, type-safe wrapper around extension messaging APIs, part of the webext-core collection.
- @webext-core/storage - Type-safe, alternative storage API for browser extensions built on webextension-polyfill.
- webext-storage-cache - Cache values in extension storage with automatic expiration and a memoize-like API for caching function results.
- webext-options-sync - Manages and auto-saves extension options forms with support for defaults and migrations across Chrome and Firefox.
- webext-dynamic-content-scripts - Automatically registers content scripts on domains added via optional permission grants at runtime.
- webext-messenger (PixieBrix) - Component-level messaging framework for browser extensions with type-safe RPC-style calls between contexts.
Plugins and CLI tools for integrating browser extension builds into modern toolchains.
- web-ext (Mozilla) - Mozilla's official CLI for building, running, linting, and signing web extensions, with live-reload for Firefox and Chromium.
- vite-plugin-web-extension (samrum) - Vite plugin for generating cross-browser ES module-based extensions from a single manifest, supporting MV2 and MV3.
- webpack-webextension-plugin - Webpack plugin that compiles WebExtension manifest.json files and adds smart auto-reload during development.
- webext-fun (fregante) - Collection of small, focused WebExtension utility packages covering patterns, permissions, content scripts, and tools.
- webext-content-scripts - Utility functions for injecting content scripts programmatically from the background in both MV2 and MV3.
Tools for unit testing, end-to-end testing, and debugging browser extensions.
- Playwright (Microsoft) - End-to-end testing framework supporting Chromium, Firefox, and WebKit, with official APIs for loading and testing extensions.
- playwright-webextext - Playwright extension library for loading Firefox add-ons and Chromium extensions from the local filesystem in tests.
- sinon-chrome - Mocks all Chrome extension APIs using Sinon stubs, enabling unit testing of extension logic in Node.js without a browser.
- @types/chrome - TypeScript type definitions for the Chrome extension API, maintained by DefinitelyTyped.
- webext-core in-memory polyfill - In-memory implementation of webextension-polyfill for unit testing extension code outside a browser environment.
- mdn/webextensions-examples - Official Mozilla repository of working Firefox add-on examples covering common extension patterns and API usage.
- Chrome DevTools Extensions Debugging - Official guide to loading unpacked extensions, using the service worker inspector, and debugging content scripts in Chrome DevTools.
Tools for automating extension uploads and publishing to browser stores via CI/CD.
- chrome-webstore-upload - Node.js library for uploading and publishing Chrome extensions to the Chrome Web Store via the Google API.
- chrome-webstore-upload-cli - CLI wrapper around chrome-webstore-upload for use in shell scripts and GitHub Actions workflows.
- web-ext sign/publish - Mozilla's web-ext CLI supports signing and submitting extensions to addons.mozilla.org via the AMO API.
- wdzeng/edge-addon - GitHub Action for publishing extensions to the Microsoft Edge Add-ons store using the Edge Add-ons API v1.1.
- wdzeng/firefox-addon - GitHub Action for publishing new versions of Firefox add-ons to addons.mozilla.org using the AMO API.
- Plasmo BPP (Browser Platform Publish) - Plasmo's built-in GitHub Action for simultaneously submitting to Chrome Web Store, Firefox Add-ons, and Edge Add-ons.
- WXT Publishing Guide - WXT's built-in publishing CLI supporting Chrome Web Store, Firefox, and Edge in a single command.
- Upload to Edge Add-ons (GitHub Marketplace) - Standalone GitHub Action for uploading extension packages directly to the Microsoft Edge Add-ons store.
Privacy-respecting analytics and payment solutions designed for browser extensions.
- ExtPay (ExtensionPay) - Payment and licensing service for browser extensions requiring no server, integrating with Stripe and supporting all major browsers.
- ExtPay GitHub - Open-source library for ExtensionPay.com with methods for checking paid status and opening payment pages from extension code.
- Plausible Analytics - Privacy-friendly, cookie-free web analytics with a lightweight script, GDPR-compliant, usable from extension options or web app sidecars.
- Umami - Open-source, self-hostable privacy-focused analytics alternative to Google Analytics, suitable for extension landing pages and companion web apps.
- PostHog - Open-source product analytics platform with session recording and feature flags, deployable self-hosted for full data control.
Tools and resources for growing installs, managing reviews, and optimizing store listings.
- Extension Booster - All-in-one growth platform for browser extension and app developers: real user reviews, install and rating tracking, competitor analysis across Chrome, Edge, Android, and Google Workspace, plus MV2-to-V3 auto-conversion.
- Chrome Web Store Listing Best Practices - Official Google guidance on writing compelling store descriptions, choosing screenshots, and improving discoverability.
- Firefox Add-ons Listing Guide (Extension Workshop) - Mozilla's best practices for user data consent disclosures, which directly affect listing approval and user trust.
- App Store Optimization (ASO) for Extensions - Chrome Web Store developer hub covering metadata, category selection, and performance metrics for store rankings.
References and tools for writing secure, privacy-respecting browser extensions.
- OWASP Browser Extension Vulnerabilities Cheat Sheet - OWASP's structured reference covering XSS, excessive permissions, insecure storage, unsafe script loading, and mitigation strategies.
- Content Security Policy for Extensions (Chrome) - Chrome's reference for the
content_security_policymanifest key, covering MV3 restrictions and allowed directives. - Content Security Policy for Extensions (MDN) - MDN guide explaining how CSP applies to extension pages, background scripts, and content scripts.
- Content Security Policy for Extensions (Edge) - Microsoft's documentation on using CSP to control resource loading in Edge extensions.
- Permissions Best Practices (Chrome) - Official guide to minimizing permission footprint, using optional permissions, and writing clear permission rationale.
- Firefox Extension Security Best Practices - Mozilla's security guide covering data handling, secure communication, and permission minimization for Firefox extensions.
Well-known, production-quality open-source extensions to learn from.
- uBlock Origin - Highly efficient ad and content blocker for Chromium and Firefox, a reference implementation for declarativeNetRequest and content script performance.
- Dark Reader - Dark mode extension for Chrome and Firefox using dynamic CSS theme generation; excellent example of large-scale content script architecture.
- Vimium - Keyboard-driven browser navigation extension in the spirit of Vim; clean, minimal CoffeeScript/TypeScript codebase.
- Refined GitHub - Extension that enhances the GitHub UI with hundreds of micro-improvements; exemplary use of content scripts and MV3 patterns.
- SponsorBlock - Crowdsourced YouTube sponsor-skip extension demonstrating efficient background API calls, content script timing, and community data pipelines.
- Bitwarden Clients - Official monorepo for Bitwarden's browser extension (Chrome, Firefox, Safari, Edge); shows Angular-based extension UI and secure storage patterns.
- Wappalyzer (Open Source) - Technology detection extension using content scripts and pattern matching; good example of large rule-set management.
- Stylus - Userstyles manager for restyling the web, a mature MV3 example with a complex options UI and storage sync.
- Violentmonkey - Open-source userscript manager for Chrome, Firefox, and Edge, demonstrating script injection and a rich settings UI.
- AdGuard Browser Extension - Full-featured ad blocker showing large-scale declarativeNetRequest rule management and cross-browser builds.
Places to ask questions, share projects, and stay current with the extension ecosystem.
- r/chrome_extensions (Reddit) - Active subreddit for Chrome extension developers and users covering development questions, reviews, and updates.
- r/firefox_extensions (Reddit) - Reddit community focused on Firefox add-on development and discovery.
- Chromium Extensions Google Group - Official discussion group for Chrome extension developers, monitored by the Chrome extensions team.
- Firefox Add-ons Community Forum (Mozilla Discourse) - Mozilla's official forum for add-on developers, including API discussions, AMO policy, and announcement threads.
- WXT Discord - Active Discord community for the WXT framework, covering usage questions, framework development, and extension ecosystem discussions.
- Plasmo Discord - Plasmo's community Discord for framework questions, templates, and sharing extensions built with Plasmo.
- Chrome for Developers Blog - Official blog with monthly "What's happening in Chrome Extensions" posts and I/O recap articles.
- Mozilla Add-ons Blog - Mozilla's official blog covering Firefox add-on news, policy updates, and developer spotlights.
On-device and in-browser AI for building intelligent, privacy-preserving extension features.
- Chrome Built-in AI (Gemini Nano) - Run on-device AI in extensions using Chrome's built-in Prompt, Summarizer, Translator, Writer, and Rewriter APIs powered by Gemini Nano.
- Prompt API for Extensions - Official guide to sending natural-language requests to Gemini Nano directly from extension service workers and content scripts.
- WebLLM - High-performance in-browser LLM inference engine using WebGPU, suitable for fully local AI features in extensions.
- Transformers.js - Hugging Face library for running machine learning models (text, vision, audio) directly in the browser with WebGPU and no server.
- chrome.sidePanel API - Official Side Panel API for hosting persistent extension UI alongside any web page.
- chrome.i18n - Official internationalization API for localizing extension UI strings and store listings.
Generators, validators, and standalone utilities that improve the extension development workflow.
- Chrome Extension Icon Generator - Browser-based tool that generates all required icon sizes (16, 32, 48, 128 px) from a single uploaded image.
- Chrome Extension Icon Generator GitHub - Open-source repository for the icon generator tool.
- Awesome-WebExtensions (fregante) - Complementary curated list by fregante focused on small utility packages and libraries for the WebExtensions API.
- webext-tools - Small collection of utility functions for common WebExtension tasks such as getting the current tab or checking context.
- webext-patterns - Utilities for working with match patterns and URL globs in browser extensions.
- webext-inject-on-install - Automatically injects content scripts into existing tabs when an extension is first installed, solving a common bootstrapping problem.
- Manifest Validator (Mozilla Discourse) - Community thread discussing available manifest validation approaches for MV3 extensions.
- webextension-toolbox generator - Yeoman generator that scaffolds a cross-browser extension project using webextension-toolbox as the compiler.
- vite-plugin-web-extension (samrum) create CLI - Interactive CLI for scaffolding new extension projects using
@samrum/vite-plugin-web-extensionwith framework choice.
See CONTRIBUTING.md for entry format rules, quality standards, and the pull request checklist. All suggestions welcome via issues or PRs.
Released under the MIT License. Copyright (c) 2026 Quang Phan.
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