A free, open-source alternative to LanguageTool browser extension. Provides grammar, spelling, and style checking using AI models, powered by your own API keys.

In January 2025, LanguageTool announced that their browser extension would become paid-only, requiring a premium subscription to use. After years of offering a free tier, they decided to restrict the browser extension exclusively to paying customers.

"We have made the difficult decision to restrict the use of the LanguageTool browser extension to Premium users." — LanguageTool

TextChecker was created as a free, open-source response to this change. Instead of paying for a subscription, you can use your own AI API keys (Google Gemini, OpenAI, or Anthropic Claude) to get the same grammar checking functionality — often with better results thanks to modern AI models.

• Multi-provider AI support: Google Gemini, OpenAI GPT, and Anthropic Claude
• Real-time checking: Grammar checked as you type (configurable)
• On-demand checking: Use keyboard shortcut (Ctrl/Cmd + Shift + G)
• Inline suggestions: Underlines errors with click-to-fix popovers
• Personal dictionary: Add words to ignore
• Statistics tracking: Track your writing improvements
• Privacy-first: Your API keys are stored locally and synced via Chrome, never sent to third-party servers

• Spelling errors
• Grammar mistakes
• Punctuation issues
• Style improvements

1. Go to the Releases page
2. Download the zip file for your browser:
   • textchecker-chrome-*.zip for Chrome, Edge, Brave, Arc
   • textchecker-firefox-*.zip for Firefox
3. Extract the zip file

Chrome / Edge / Brave / Arc:

1. Go to chrome://extensions/ (or edge://extensions/, brave://extensions/)
2. Enable "Developer mode" (toggle in top right)
3. Click "Load unpacked"
4. Select the extracted folder

Firefox:

1. Go to about:debugging#/runtime/this-firefox
2. Click "Load Temporary Add-on"
3. Select any file from the extracted folder

1. Clone this repository:

   git clone https://github.com/yourusername/textchecker.git
   cd textchecker

2. Install dependencies:

   npm install

3. Build the extension:

   npm run build

4. Load the extension in Chrome:

   • Go to chrome://extensions/
   • Enable "Developer mode"
   • Click "Load unpacked"
   • Select the .output/chrome-mv3 folder

1. Click the TextChecker icon in your browser toolbar
2. Click the settings icon to open the options page
3. Add your API key for at least one provider:
   • Google AI Studio (Gemini)
   • OpenAI Platform
   • Anthropic Console
4. Choose your preferred provider and model
5. Select check mode (real-time or on-demand)

# Start development server with hot reload
npm run dev

# Build for production
npm run build

# Build for Firefox
npm run build:firefox

# Create distribution zip
npm run zip

• WXT - Chrome Extension Framework
• React - UI Library
• Tailwind CSS - Styling
• Vercel AI SDK - Multi-provider AI Integration
• TypeScript - Type Safety

TextChecker supports grammar checking in multiple languages including:

• English
• German
• Spanish
• French
• Portuguese
• And many more (auto-detected)

• Your API keys are stored in Chrome's sync storage and are never sent anywhere except directly to the AI provider you choose
• Text is only sent to the AI provider when checking grammar
• No analytics or tracking
• Fully open source - audit the code yourself

Contributions are welcome! Please feel free to submit a Pull Request.

MIT License - see LICENSE file for details.

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• Created as a free alternative after LanguageTool's decision to go premium-only
• Built with WXT
• Powered by Vercel AI SDK