LanguageTool
Early StageOpen-source multilingual grammar and style checker
👥 5M+ users💰 Bootstrapped, profitable
✓ Last verified: March 2026
LanguageTool is an open-source grammar, style, and spell checking tool that supports over 30 languages with deep linguistic analysis. It goes beyond basic grammar checking to detect stylistic issues, redundancies, and context-dependent errors, making it a strong privacy-focused alternative to proprietary grammar checkers.
Our Ratings
9
Ease of Use
7
Output Quality
9
Value
5
Support
7
Versatility
Key Features
- ✓Grammar and style checking in 30+ languages
- ✓Context-aware error detection beyond simple spell check
- ✓Picky mode for advanced stylistic suggestions
- ✓Self-hosted option for maximum data privacy
- ✓Add-ons for all major browsers, email clients, and office suites
Best For
- 👍 Multilingual writers needing grammar support across languages
- 👍 Privacy-conscious users who want a self-hostable grammar tool
- 👍 Teams standardizing writing quality without vendor lock-in
Limitations
- ⚠️ Free tier has a 10,000 character per check limit
- ⚠️ English rule coverage is not as deep as Grammarly for advanced suggestions
- ⚠️ Some language support is more mature than others
Integrations
Google DocsMicrosoft WordLibreOfficeChrome ExtensionFirefox ExtensionThunderbird
Quick Facts
DifficultyBeginner
Team sizeany
API accessYes
Mobile appYes
Data privacyhigh