What You're Building

You will create a browser extension compatible with Chrome and Firefox that enhances existing websites by injecting content scripts, providing a popup UI for user interaction, and running background service workers for persistent tasks. The extension will be packaged with Manifest V3 standards and ready for submission to the Chrome Web Store, enabling you to distribute your functionality to users seamlessly.

Before You Start

Ensure you have developer accounts for the Chrome Web Store and Firefox Add-ons. Decide whether your UI will be built with Vanilla JavaScript or React based on your familiarity and project complexity. Install and configure your preferred code editor (Cursor or Windsurf recommended). Familiarize yourself with Manifest V3 specifications and prepare GitHub repositories for version control and CI/CD setup.

Step-by-Step Approach

  1. Set up your project structure: Initialize your extension folder with manifest.json, popup HTML/JS, content scripts, and background service worker files. Use Lovable or similar boilerplate to scaffold Manifest V3 files correctly.
  2. Develop content scripts: Write JavaScript that injects into target websites to modify DOM or add functionality. Test scripts locally using Chrome’s extension developer mode.
  3. Build the popup UI: Create a user interface accessible from the browser toolbar. Use React if you need complex state management or Vanilla JS for simpler UIs. Ensure it communicates with background scripts via messaging.
  4. Implement background service worker: Handle persistent tasks like alarms, event listeners, or API polling. Remember Manifest V3 uses service workers instead of background pages.
  5. Test your extension thoroughly: Use Chrome and Firefox developer tools to debug scripts, check permissions, and verify UI behavior. Test edge cases and error handling.
  6. Set up GitHub Actions: Automate linting, testing, and packaging your extension. Configure workflows to publish new versions to the Chrome Web Store automatically on tagged releases.
  7. Submit to stores: Prepare screenshots, descriptions, and privacy policies. Upload your packaged extension to the Chrome Web Store and Firefox Add-ons, then monitor for approval and user feedback.

Realistic Time Estimates

  • First prototype: 1-2 days to scaffold the project, inject basic content scripts, and create a minimal popup UI.
  • MVP: 1-2 weeks to implement full functionality, background service worker logic, and basic testing.
  • Production-ready: 3-4 weeks including thorough testing, CI/CD pipelines, store submission, and user documentation.

Common Mistakes and How to Avoid Them

  • Ignoring Manifest V3 restrictions: Service workers replace background pages and have lifecycle constraints. Avoid long-running tasks in background scripts; use alarms or message passing instead.
  • Over-permissioning: Request only necessary permissions in manifest.json to prevent store rejection and user distrust.
  • Not testing on both Chrome and Firefox: APIs and behaviors differ slightly; test on both browsers early to catch compatibility issues.
  • Neglecting CI/CD automation: Manual packaging and publishing lead to errors and delays. Use GitHub Actions to automate builds and deployments.

When Vibe Coding Works Well Here

Vibe Coding accelerates iterative development with AI-assisted coding and lightweight editors, ideal for building popup UIs and content scripts quickly. Its integration with GitHub Actions streamlines deployment, making it perfect for developers who want to prototype and ship extensions fast without complex setups.

When It Doesn't

If your extension requires complex native messaging, heavy background processing, or extensive multi-platform support beyond Chrome and Firefox, Vibe Coding’s current toolset may fall short. Also, if you prefer full IDE features or offline development, browser-based editors like Windsurf might feel limiting.