browser-extension-development

Development v2.0.1

Build cross-browser extensions with WebExtensions API, Manifest V3, WXT/Plasmo, testing, and publishing

browser-extensionwebextensionsmanifest-v3wxtchromefirefoxtypescripttesting

Overview

Comprehensive browser extension development toolkit covering scaffolding, cross-browser compatibility, testing, and store publishing. Uses WXT framework as the 2026 standard for production extensions.

Workflow

  1. Scaffold new extension project with WXT or Plasmo framework
  2. Configure manifest with minimal permissions and Firefox support
  3. Implement service workers, content scripts, and message passing
  4. Set up testing with Vitest (unit) and Playwright (E2E)
  5. Build and publish to Chrome Web Store and Firefox AMO

Installation

claude plugin install browser-extension-development

Quick Start

Ask about creating a new browser extension or use the browser-extension-developer agent

Examples

Generates complete WXT project with TypeScript, manifest, and testing

Create a new browser extension for bookmarking pages

Converts background scripts, updates APIs, handles Chrome 144+ changes

Migrate my MV2 extension to Manifest V3

Configures unit and E2E testing with Chrome API mocks

Add Vitest and Playwright testing to my extension

Analyzes Chrome 144+ breaking changes and implements fix

My extension's message passing stopped working in Chrome

Validates manifest, creates builds, sets up CI/CD automation

Help me publish to Chrome Web Store and Firefox AMO

Dependencies

Required

    Optional

      Constraints

      • Chrome MV3 required for Chrome Web Store (MV2 removed June 2025)
      • Firefox requires browser_specific_settings with gecko ID
      • Chrome 144+ requires explicit return true/false from message listeners
      • Service workers have 30s idle timeout in Chrome (use storage for state)
      • No inline scripts allowed in MV3 (CSP restriction)