Chrome Extension — Cursor + Railway
Browser extension with backend sync
Chrome Extension (Manifest V3) with a Railway backend for data sync, Clerk auth, and Lemon Squeezy payments.
What's Included
Extension MV3
Manifest V3 with popup, content script, service worker
Auth Sync
Clerk auth synced between extension and web app
Payments
Lemon Squeezy for one-click purchases
Backend Sync
Real-time data sync via Railway API
Setup Guide
Clone and install
$ git clone https://github.com/gptsters/extension-starter my-extension && cd my-extension && npm install
Set up Clerk
Auth for both extension and web dashboard.
Add to .env.local
NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY=
CLERK_SECRET_KEY=
Load extension in Chrome
Go to chrome://extensions, enable Developer Mode, click Load Unpacked, select /extension folder.
💡 Reload the extension after every code change.
Cursor Prompt
Paste this into Cursor to generate the full codebase
Build a Chrome Extension (Manifest V3) with: 1. Popup UI (React + Tailwind): shows user data, toggle features 2. Content script: injects functionality into web pages 3. Service worker: handles background tasks and API calls 4. Options page: settings and preferences Backend (Next.js on Railway): - Clerk auth synced with extension - D1 database for user data - API routes for sync Start with manifest.json, then popup, then content script.
Tools You'll Need
Based on this starter's stack
Some links are affiliate links.
Common Issues
Related Starters
Frequently Asked Questions
~35 minutes. The setup guide walks you through every step with copy-paste commands. No guesswork.
Free to start. Railway's free tier includes 500 hours/month.
Yes. The starter kit gives you a working foundation. Use the included Cursor prompt to add features specific to your product.
Check our integration guides at /integrations and prompt library at /prompts for step-by-step instructions on adding any feature.