OpenGrammar is the free, open-source Grammarly alternative. Run local rule-based checks offline, or plug in your own AI API key for advanced edits without paying monthly subscriptions.
Most popular grammar assistants require you to send every keystroke to their servers and charge a hefty monthly fee for advanced features. OpenGrammar changes that. The core engine runs locally in your browser, checking for passive voice and repetition without needing a server.
Designed for developers, writers, and privacy advocates who want complete control over their writing environment.
No databases, no user accounts. The local engine runs offline. AI requests are sent to a stateless edge function and immediately forgotten.
Paste in your API key for OpenAI, Groq, OpenRouter, or Together. Pay fractions of a cent per month directly to the provider instead of a $12/mo subscription.
Don't want to use our proxy? Deploy your own Cloudflare Worker or Vercel Edge function in a single command. You own the entire infrastructure.
Checks for passive voice, repeated words, and overly long sentences right in your browser. Fast, free, and completely offline.
For complex grammar, tone rewriting, and clarity suggestions, text is sent securely to an LLM using your personal API key.
See red, yellow, and blue underlines as you type. Click to accept suggestions, ignore them, or add words to your custom dictionary.
Start writing better today without sacrificing your privacy or your wallet.
# 1. Clone the repository
git clone https://github.com/swadhinbiswas/opengrammar.git
# 2. Build the extension
cd opengrammar/extension
bun install
bun run build
# 3. Load unpacked in Chrome
Go to chrome://extensions, enable Developer Mode, and select the dist/ folder.