LanguageTool vs Grammarly
Last verified · repository stats fetched 27 Oct 2026
Both check spelling, grammar and style as you type in the browser and other apps. LanguageTool is open source, covers more than 30 languages and can run on your own server. Grammarly runs in its cloud and builds its paid plan around AI rewriting and generation.
| LanguageTool | Grammarly | |
|---|---|---|
| Licence | LGPL-2.1 Open source (copyleft) | Proprietary Freemium or paid |
| Source code | GitHub | Not open source |
| ★ Stars | 15.2k 15,201 | n/a |
| Last commit | 27 Oct 2026 | n/a |
| Runs on | Windows, macOS, Linux, Web | Not available |
| Price | Free tier; Premium for individuals and teams | Free tier; Pro listed at $12 (USD) |
| Self-hosting | Yes (local HTTP server, no AI rules) | Not available |
| Free alternative to | Grammarly, ProWritingAid, Hemingway Editor | — |
Key differences
- LanguageTool covers 30+ languages; Grammarly's Pro plan includes help to 'write fluently in English'. (languagetool.org/premium · grammarly.com/plans)
- LanguageTool's free tier checks up to 2,000 characters per text field and includes 3 AI rephrasings a day; Premium raises that to 150,000 characters and adds 20,000+ extra checks in major languages. (languagetool.org/premium)
- LanguageTool can run as a local HTTP server that the browser add-on can use, though that self-hosted version has no AI-based rules, which are cloud-only. (dev.languagetool.org/http-server)
- Grammarly Free covers spelling and grammar and 100 AI prompts a month; Pro adds full-sentence rewrites, tone adjustment, plagiarism and AI-text detection and 2,000 prompts a month. (grammarly.com/plans)
- Grammarly Pro is listed at $12 (USD) on its plans page. (grammarly.com/plans)
Which should you pick?
- LanguageTool: Pick LanguageTool if you write in languages other than English, want open-source software, or need checking on your own server without sending text to a cloud.
- Grammarly: Pick Grammarly if you write mainly in English and want AI rewriting, tone controls and plagiarism checks in one paid plan.
This verdict is based on the documented facts above, not on hands-on testing.
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Other comparisons
Sources: languagetool.org/premium · grammarly.com/plans · dev.languagetool.org/http-server. Stars and last-commit dates come from each project's public repository. “Not available” or “Not documented” means we found no official source for it, not that the feature is missing.