rewrite.so™

Write freely. Send confidently.

rewrite.so is an input-box-level AI rewrite engine. Translation, error correction, and tone polishing are all unified into a single Rewrite Engine. The entire interaction collapses into one gesture (double-tap Shift), and the UI is invisible by default — only an 8 px translucent dot appears when an editable input is focused. It does not steal focus, does not break your flow.

• 🎯 Three fixed styles — faithful, casual, formal. Always three, no more.
• ⌨️ Keyboard-only — double-tap Shift to summon, 1/2/3 or ↑/↓ + Enter to accept, Esc to dismiss.
• 🔒 Privacy by architecture — input text and rewrite output are never persisted, anywhere. Password / CC / CVV / OTP fields are hard-excluded by design.
• 🌐 Cross-language by default — auto-detects the page language; cross-language rewriting is just implicit translation.
• 🔧 BYOK — signed-in users can plug in their own OpenAI-compatible API key for unlimited usage.

Quick start (development)

Prerequisites

• Node 22+
• pnpm 9+
• A Cloudflare Workers Paid plan ($5/mo). Required for Durable Objects and CPU > 10 ms.

Install

git clone https://github.com/rewrite-so/rewrite.so.git
cd rewrite.so
pnpm install
cp .env.example .env.local
# Fill in OPENAI_BASE_URL / OPENAI_API_KEY / OPENAI_MODEL, etc.

Run end-to-end locally

Open three terminals:

# Terminal 1: mock upstream (skip if you have a real OpenAI-compatible key).
node scripts/mock-upstream.mjs        # listens on 127.0.0.1:9999

# Terminal 2: API.
cp apps/api/.dev.vars.example apps/api/.dev.vars
pnpm dev:api                          # http://localhost:8787

# Terminal 3: Web.
cp apps/web/.env.local.example apps/web/.env.local
pnpm dev:web                          # http://localhost:3000

# Extension: load apps/extension/dist as an unpacked extension at chrome://extensions
pnpm dev:ext

Known gotcha (macOS users): If your shell has HTTP_PROXY / HTTPS_PROXY set, wrangler dev will route fetch() inside the worker through that proxy — even calls to localhost:9999. Unset the proxy variables before starting pnpm dev:api, or:

env -u HTTP_PROXY -u http_proxy -u HTTPS_PROXY -u https_proxy \
    -u ALL_PROXY -u all_proxy pnpm dev:api

Check & build

pnpm typecheck    # TS type-check across all packages
pnpm test         # vitest across all packages
pnpm lint         # biome
pnpm fix          # biome auto-fix
pnpm build        # build all packages

Deployment (CI/CD)

Deploys are automated via GitHub Actions in .github/workflows/:

Workflow	Trigger	Behavior
ci.yml	PR + push to main	lint + typecheck + test
deploy-api.yml	push to main touching apps/api/ or packages/	Deploys to api.rewrite.so
deploy-web.yml	push to main touching apps/web/ or packages/	OpenNext build + deploys to rewrite.so
release-extension.yml	tag ext-v*	Builds zip + creates GitHub Release
migrate-d1.yml	manual dispatch	Runs D1 migrations remotely

First-time setup: GitHub repo → Settings → Secrets and variables → Actions, add two repository secrets:

• CLOUDFLARE_API_TOKEN — needs Workers Scripts:Edit + Workers KV Storage:Edit + D1:Edit + Zone DNS:Edit
• CLOUDFLARE_ACCOUNT_ID

Release the extension:

The extension is published on the Chrome Web Store: chromewebstore.google.com/detail/gheiendipgcgiligfmbimbbffkkfiamk.

To cut a new version:

git tag ext-v0.1.0 && git push --tags

The action builds a zip and creates a GitHub Release. Each new version still needs to be uploaded manually to the Chrome Web Store Developer Dashboard for review — the GitHub Release artifact is the source zip you upload there.

Manual deploy (bypass CI):

pnpm --filter @rewrite/api deploy   # requires CLOUDFLARE_API_TOKEN env
pnpm --filter @rewrite/web deploy

Repository layout

rewrite.so/
├── apps/
│   ├── api/         Cloudflare Workers + Hono   → api.rewrite.so
│   ├── web/         Next.js + OpenNext           → rewrite.so
│   └── extension/   Vite + CRXJS Chrome MV3
├── packages/
│   ├── core/        Input watcher, trigger, overlay UI (vanilla DOM, shared by web + extension)
│   ├── prompts/     The three system prompts
│   └── shared/      SSE frame types, shared constants, i18n strings
└── docs/            Architecture / SSE protocol / D1 schema / BYOK / privacy

Tech stack

• Infrastructure — Cloudflare (Workers / D1 / Durable Objects / KV / Turnstile)
• API — Hono on Workers, 3-way concurrent SSE multiplexing, strict OpenAI Chat Completions wire format
• Web — Next.js 15 App Router via @opennextjs/cloudflare → Workers
• Extension — Chrome MV3 + Vite + CRXJS + Preact (popup / options only)
• Auth — better-auth + drizzle adapter (limited to its 4 internal tables; everything else is hand-written SQL)
• Payments — Creem as Merchant of Record ($13.99/mo or $7.99/mo billed annually)
• Code quality — TypeScript + Biome + vitest + Playwright

Internationalization

The UI supports 7 locales: en (default) · zh-CN · ja · ko · es · fr · de.

• Source of truth: packages/shared/src/messages/{locale}.json
• Routing: localePrefix: 'as-needed' — English at /, others at /{locale}/...
• Adding a language: see docs/i18n.md for the step-by-step
• Validate: pnpm i18n:validate (also runs in CI on every PR)

UI locale and rewrite content locale are independent: a user reading the site in English may still ask for rewrites in Japanese.

Known unsupported

• Google Docs (canvas-rendered editor)
• Gmail compose (iframe + complex contenteditable)
• Inputs inside iframes (MV3 all_frames: false)
• Firefox / Safari (planned for v0.2)

Contributing

Bug reports, fixes, and PRs are welcome. Please read CONTRIBUTING.md before opening a PR. We follow the Contributor Covenant Code of Conduct.

License & trademark

Code is licensed under Apache License 2.0.

The name rewrite.so™, the rewrite wordmark in connection with AI text rewriting, and the visual identity are unregistered trademarks of Lin Shuaibin and are not covered by the Apache license. See TRADEMARK.md for details.

Self-hosting & forks (TL;DR)

✅ Self-host for personal or internal team use — go ahead, no permission needed.

✅ Fork and modify under a different name — pick something distinct (e.g. MyEditorAI), replace UI copy, and you’re free to redistribute.

❌ Do not run a hosted SaaS under the name rewrite.so, rewrite, or any confusingly similar variant. The trademark exists so users know what they’re getting when someone recommends "rewrite.so".

Full policy: TRADEMARK.md. Questions: hello@rewrite.so.