Embedwright

Embedwright ships an AI writing assistant in two parts: a Next.js web app with accounts, saved prompts and history, and a browser extension that rewrites selected text on any page. The extension shares auth with the web app through a token handshake. Stripe subscriptions gate higher limits, and a settings page lets users bring their own API key instead.

It is opinionated about the extension as the main surface, since that is where people actually write. Build scripts produce Chrome and Firefox packages. The limitation: store review is your job, and extension permissions for all sites can slow approval. The docs explain how to narrow them, but the default is broad.