LanguageTool
The open-source grammar checker that speaks 31 languages
LanguageTool (acquired by Learneo) is the only grammar checker with an open-source core (LGPL 2.1, 13.8K GitHub stars). 31 languages, self-hostable. Premium at $4.99/mo — half the price of Grammarly.
LanguageTool is an artificial intelligence tool in the Text & Writing category, developed by LanguageTooler GmbH (Learneo) and launched in 2003. LanguageTool (acquired by Learneo) is the only grammar checker with an open-source core (LGPL 2.1, 13.8K GitHub stars). 31 languages, self-hostable. Premium at $4.99/mo — half the price of Grammarly. Key features include: 31 supported languages, Open-source core (LGPL 2.1), AI rewriting (via OpenAI), 10,000 char. free per check, Browser extension (Chrome, Firefox, Edge, Safari), Self-hostable (Docker/Java). The tool is available on web, ios, android, api with a freemium pricing model.
💰 Pricing
✨ Features
🎯 Use Cases
- Native multilingual correction
- Multilingual writing
- Academic verification
- Professional emails
⚖️ Pros & Cons
👍 Pros
- The only grammar checker with an open-source core: you can self-host it on your own servers
- 31 languages supported — the broadest multilingual support among grammar checkers on the market
- Half the price of Grammarly (~$5/mo vs ~$12/mo) for comparable features
- GDPR compliant with texts not stored — privacy by default
- Native integrations with LibreOffice, Word, Google Docs and VS Code
👎 Cons
- Acquisition by a US company transferred data control to California — contradicts the EU open-source image
- AI rewriting sends your texts to a third-party provider — caution with sensitive content
- No built-in plagiarism detection — you will need a complementary tool
🏆 Verdict
In summary, LanguageTool stands out in the text & writing AI landscape thanks to its strengths: the only grammar checker with an open-source core: you can self-host it on your own servers, 31 languages supported — the broadest multilingual support among grammar checkers on the market, half the price of grammarly (~$5/mo vs ~$12/mo) for comparable features. However, some users note: acquisition by a us company transferred data control to california — contradicts the eu open-source image, ai rewriting sends your texts to a third-party provider — caution with sensitive content. If you're looking for alternatives, you can compare LanguageTool with DeepL, Grammarly, QuillBot. Our overall rating: 3.9/5.
ℹ️ Information
| Company | LanguageTooler GmbH (Learneo) |
|---|---|
| Launched | 2003 |
| Platforms | WEB, IOS, Android, API |
| Category | Text & Writing |
| Site | https://languagetool.org |