LanguageTool

LanguageTool is an open-source grammar and style checker supporting 30+ languages with privacy-friendly self-hosting options.

Overview

LanguageTool stands out for its multilingual reach and openness. It checks grammar, spelling, punctuation, and style in more than 30 languages and dialects, with particularly strong coverage for European languages beyond English. The tool integrates with browsers, email clients, Word, Google Docs, and LibreOffice, and its premium tier adds style and tone suggestions plus paraphrasing. Because the core engine is open source, organizations can self-host LanguageTool to keep sensitive text inside their own infrastructure. Its rule-based and statistical engines complement each other: hard grammar rules catch clear errors while statistical models flag stylistic awkwardness. Teams can add shared dictionaries so product names and internal jargon never trigger false corrections. Because the project is open source, the community contributes language rules continuously.

Key Features

• Grammar, spelling, and style checking in 30+ languages including German, French, and Spanish
• Open-source core that can be self-hosted for maximum data privacy
• Integrations with browsers, Word, Google Docs, LibreOffice, and email clients
• Style and tone suggestions that improve clarity beyond basic correctness
• Paraphrasing and sentence rewrites on premium plans
• Personal dictionary and rule customization for team-specific terminology
• Fast, lightweight checking suitable for real-time editor feedback

Pricing

LanguageTool is freemium. The free tier covers solid grammar and spelling checks with a text-length limit per request; Premium adds advanced style checks, tone detection, and paraphrasing at a low monthly price. Self-hosted enterprise deployments are available for organizations with strict data policies. Enterprise self-hosting is priced by organization, and the premium individual plan costs less than most English-only competitors.

Who Is It For

LanguageTool is for multilingual writers, European teams, and privacy-conscious organizations that need grammar support beyond English or want to keep text processing on their own servers. Multilingual companies standardizing on one checker across offices find the language breadth especially practical.

FAQ

Is LanguageTool free to use?

Yes, the open-source version and free web tier are usable at no cost; Premium unlocks advanced style and paraphrasing features. The free tier covers everyday checking; style and tone features require the premium subscription.

Does LanguageTool offer an API?

Yes, LanguageTool offers a public proofreading API and a self-hosted server, making it one of the most developer-friendly grammar tools available. The public API is rate-limited for free users and scales on paid and self-hosted plans.

How does LanguageTool compare to alternatives?

LanguageTool covers more languages and offers self-hosting, while Grammarly provides deeper English style coaching and wider consumer app coverage. LanguageTool is the clear choice when more than English matters; Grammarly still leads for English-only polish.