Introduction
LanguageTool is a multilingual AI grammar and style checker that supports over 30 languages — making it the leading Grammarly alternative for non-English writers and privacy-conscious users. Available as a browser extension, desktop app, Microsoft Office add-in, and fully open-source self-hosted solution, LanguageTool provides comprehensive grammar, punctuation, style, and word choice corrections without requiring English as the primary language.
LanguageTool targets multilingual professionals, academic writers, journalists writing in languages beyond English, and privacy-focused users who want powerful grammar checking without sending data to third-party AI services. Its open-source core and self-hosting option make it unique among commercial writing tools.
The key differentiator is language coverage: while Grammarly and ProWritingAid are optimized for English, LanguageTool provides sophisticated grammar analysis for German, French, Spanish, Portuguese, Polish, Dutch, and 25+ other languages with the same depth of correction that English-only tools provide for their single language.
Prices are subject to change. Check official pricing.
- Free: $0/month — basic grammar and spelling checks, browser extension, limited style suggestions
- Premium (Individual): From ~€4.99/month (billed annually) — advanced style suggestions, punctuation, phrasing improvements, no word limit, higher API limits
- Team Plan: From ~€4.74/user/month — team management, centralized billing, all Premium features
- Self-hosted (Open Source): Free — download and run locally, full privacy, no data sent externally
Getting Started
Install the LanguageTool browser extension from Chrome, Firefox, Edge, or Safari extension stores. The extension works across all websites and web applications — Gmail, Google Docs, WordPress, LinkedIn, and more. A Google Docs add-on provides deeper integration with the document editor. Desktop apps are available for Windows and Mac for offline use.
Select your primary language in the extension settings, and LanguageTool begins checking immediately in all text fields across your browser. The interface mirrors standard grammar tool conventions — colored underlines for corrections, right-click to see suggestions, accept or dismiss each recommendation.
Core Features
30+ Language Support: LanguageTool provides production-quality grammar checking for German, French, Spanish, Catalan, Dutch, Polish, Portuguese (Brazil and Portugal), Russian, Italian, and 20+ additional languages. The depth of analysis — including complex agreement rules, stylistic improvements, and regional spelling variants — rivals Grammarly's English-only capabilities in supported languages.
Style and Clarity Analysis: Beyond grammar, LanguageTool Premium identifies wordy phrases, redundant expressions, weak word choices, and inconsistent spelling. Style rules are configurable — users can enable or disable specific rule categories based on their writing context (academic, journalistic, business).
Open Source and Self-Hosting: LanguageTool's core grammar engine is open source (LGPL license) and available on GitHub. Developers and privacy-conscious users can run a full local instance — all text remains on the local machine, never transmitted to external servers. This makes LanguageTool suitable for sensitive documents in legal, medical, and government contexts where data cannot leave the organization.
API Access: LanguageTool provides a public API and a more capable private API for developers. The API enables grammar checking integration into custom applications, CMS platforms, and content workflows without requiring the user-facing browser extension.
First Project Tutorial
Install the Chrome extension, open a new Gmail compose window, and select your language from the LanguageTool menu icon. Write your email — mistakes are underlined in the LanguageTool color scheme (red for errors, yellow for style suggestions). Click any underline to see the correction with an explanation in your chosen language. The explanation is particularly valuable for language learners and non-native speakers who want to understand the grammar rule behind each correction.
For the self-hosted setup, download the LanguageTool server from GitHub and run it locally as a Java service. Configure your browser extension to point to localhost instead of the LanguageTool cloud API. All text checking then runs entirely on your machine with zero external data transmission.
Best Practices and Optimization
Configure custom word lists in LanguageTool settings for domain-specific terminology that the tool incorrectly flags. Technical writers and developers frequently add programming terms, product names, and jargon to the whitelist to reduce false-positive corrections in technical documentation.
For multilingual writing workflows, switch LanguageTool's active language to match each document. The extension supports per-tab language switching, enabling seamless grammar checking across simultaneous projects in different languages without reconfiguring settings.
Pros and Cons
- Pros: Best multilingual coverage of any grammar tool (30+ languages); open source with self-hosting option for full data privacy; strong free tier; API access for developer integration; no word count limits on Premium; works in non-English languages with Grammarly-equivalent depth
- Cons: English-language suggestions are not as refined as Grammarly; interface design is less polished than premium competitors; self-hosting requires Java server setup; fewer AI writing features than Grammarly Pro; Premium pricing in some regions is confusing
What Users Are Saying
LanguageTool is strongly recommended in privacy-conscious communities and by non-English writers who find Grammarly's English-only optimization inadequate. Self-hosting capability is frequently cited as the deciding factor for users who handle sensitive client or organizational documents.
Have you used LanguageTool? Share your experience in the review section below.
Summary
LanguageTool is the most powerful multilingual grammar checker available and the best alternative to Grammarly for writers who work in languages beyond English. Its open-source core, self-hosting capability, and strong free tier make it accessible to individuals, developers, and organizations with strict data privacy requirements. For non-English writing workflows or any context where data sovereignty is a concern, LanguageTool provides capabilities that no other writing tool can match.
