# LanguageTool

> Grammar checker covering 31 languages with an LGPL open-source core you can self-host for free — the widest multilingual support in this category.

Source: https://selfpublishingdirectory.com/writing-tools/languagetool
Website: https://languagetool.org
Category: Writing Tools (https://selfpublishingdirectory.com/writing-tools)
Pricing: freemium — $0–$239
AI-powered: yes
Tags: grammar-checker, multilingual, open-source, self-hosted, browser-extension, privacy, affordable, style-checking
Last verified: 2026-08-20
Best For: Non-English manuscripts, and authors who want a grammar checker they can self-host
Collaboration: no
Platform: web, mac, windows, ios, chrome-extension
Tool Type: grammar-checker

LanguageTool is a rules-based grammar checker covering 31 languages with full grammar support — the widest multilingual coverage in this category. Its LGPL-2.1 core is self-hostable, which now matters more than it used to: in December 2025 the browser extension moved behind a Premium paywall, making a self-hosted server the only free way to check text outside the web app.

## What You Get

- **31 languages with full grammar rules:** Arabic through Ukrainian, including German, French, Spanish, Portuguese, Polish and Chinese. Norwegian is a 32nd language but spellcheck-only.
- **Self-hostable open-source core:** LGPL-2.1-or-later on GitHub and actively maintained (v6.8, May 2026). Community Docker images run an unlimited private server on your own machine.
- **Picky Mode and a personal dictionary:** Optional stylistic strictness beyond basic grammar, plus a custom word list so character and place names stop getting flagged.
- **Native apps and office plugins:** macOS and Windows desktop apps, an iOS app, and add-ins for MS Word, Google Docs and LibreOffice. No first-party Android app.
- **AI rephrasing:** Sentence-level paraphrasing, 3 per day free and unlimited on Premium.

## Who It's For

- **Authors writing outside English:** Nothing else in this category comes close on German, French, Spanish, Portuguese or Polish.
- **Authors who won't upload an unpublished manuscript:** The self-hosted server never sends a word off the machine, and costs nothing.
- **Budget-conscious English-language authors:** Around $60/yr is the cheapest credible paid grammar tool — but read the extension caveat below first.

**Pricing:** Free tier is web-checker-only — 2,000 characters per check (~350 words) and 3 AI rephrases per day. Premium is priced in EUR through a geo-keyed checkout: €19.90 monthly, €39.90 quarterly, €59.89 per year (~€4.90/mo), or €99.90 for two years (~€4.16/mo). Teams is €56.90 per user per year up to 20 seats, contact-sales above that. Students and teachers get 20% off with code EDUCATION. 14-day money-back guarantee on all Premium purchases.

## Strengths

- **Multilingual depth no competitor matches:** ProWritingAid, Grammarly and AutoCrit are English-first. This is the only credible option for a German or Spanish manuscript.
- **Genuinely self-hostable:** Current releases, working Docker images, no character cap and no subscription on your own server.
- **No AI training on your text, by default:** A December 2024 terms update stopped customer input being used to train its models, with no opt-in required. Grammarly defaults training on for free and individual Pro accounts.
- **Cheapest credible annual price:** Roughly $60/yr against Grammarly Pro's $144/yr.

## Limitations

- **The browser extension is Premium-only since December 2025:** Chrome, Firefox, Edge and Safari extensions now require a subscription — free users get 14 days, then the extension stops working. This was the free tier's headline feature.
- **Two different character caps:** 150,000 characters (~25,000 words) in the web app and API, but 100,000 per check in the browser extension. Chapter-by-chapter either way, not whole-manuscript.
- **No fiction awareness:** No pacing, dialogue or genre reports. Like Grammarly, it flags intentional fragments and dialect-heavy dialogue as errors.
- **"German company" no longer implies EU data residency:** Founded in Potsdam in 2003, but Learneo, Inc. (California) acquired it in April 2023 and is the data controller named in the current terms.

## Alternatives

[ProWritingAid](/writing-tools/prowritingaid) is the pick for English-language fiction — manuscript reports and native Scrivener integration LanguageTool has no answer for. [Grammarly](/writing-tools/grammarly) still ships a free browser extension, now the clearest reason to pick it instead, though it runs $144/yr and defaults AI training on. [QuillBot](/writing-tools/quillbot) also has a free extension — and LanguageTool's own paywall notice sends displaced users there, since Learneo owns both.