What is ExtensionStart?
A plain-English overview of ExtensionStart: a production-grade WXT + React 19 starter kit for building paid MV3 browser extensions with working auth, Stripe billing, and policy-safe paywalls.
ExtensionStart is a starter kit for developers who want to ship a paid browser extension without spending months on the plumbing. You buy access to a private GitHub repository containing a complete, tested monorepo, then build your product on top of it.
What’s actually in the box
The kit is a pnpm + Turborepo monorepo built on WXT, React 19, and Tailwind 4, with a Firebase backend:
- Auth that works in MV3. Web-style Firebase sign-in doesn’t work in a service worker; the kit ships a Google sign-in flow that does, with an anonymous-first mode that links accounts without losing data.
- Stripe billing the server enforces. Checkout, customer portal, and webhook-written entitlements on Cloud Functions. Clients can never grant themselves paid features.
- A monetization gate engine. Triggers, cooldowns, and presets designed to stay inside Chrome Web Store policy: free value first, walls that dismiss, no install-time paywalls.
- Tests at every layer. 411 unit tests plus 12 Playwright specs that run against the real built extension, catching the failures unit tests miss.
Who it’s for
Indie developers and small teams who know TypeScript and want the revenue-critical parts (sign-in, payments, paywalls) already solved and tested. It supports Chrome and Edge (MV3) plus Firefox from one codebase.
What it isn’t
It’s not a subscription, not a SaaS dependency, and not a no-code builder. It’s source code: one purchase, your repo access, your Stripe account, your revenue.
Frequently asked questions
Is ExtensionStart a no-code tool?
No. It's a codebase for developers: a pnpm + Turborepo monorepo you clone, configure, and build your own extension on top of. You should be comfortable with TypeScript and React.
Do I need my own Stripe and Firebase accounts?
Yes. The kit wires them together for you (a setup wizard walks through Firebase and Stripe configuration, and API-driven scripts create the Stripe products and webhooks), but the accounts, keys, and revenue are entirely yours.
How is this different from a template?
Templates give you a popup and a build script. ExtensionStart ships the parts that usually take months: MV3-compatible Google sign-in, server-enforced entitlements, a Chrome-Web-Store-policy-safe gate engine, and 400+ automated tests that run against the real built extension.