Notes 
Great alternative to Grammarly. Plugins and apps available for: Firefox, Chrome, Edge, Safari, Opera, iOS, macOS, Windows, Google Docs, Microsoft Office, LibreOffice, OpenOffice, Gmail, Apple Mail and Thunderbird.
Reviewed by Marco Wollank
LanguageTool
languagetool.org 3 ratings so far*
Rate LanguageTool: No account needed
Threat level
Covered
A covered pick. Anyone can use it as a private drop-in, with no setup or know-how. Enough for most people. Threat levels
Our take
A legitimate open-source answer to Grammarly, and the killer feature is that you can self-host the server so your writing never leaves your network, which is exactly what Grammarly can’t offer. The trade is that the free hosted tier checks shorter text and the advanced suggestions push you toward a subscription. For privacy-minded writers the move is clear: self-host the engine if your text is sensitive, or use the free plugins for casual fixes. Choose this over Grammarly whenever you’d rather not feed a US cloud every sentence you type.
GitHub at a glance
languagetool-org/languagetool LGPL-2.1 grammarnatural-languagenatural-language-processingproofreadingspellcheckstyle-checker
Stars
15,231
+27 this week
Forks
1,599
161 watching
Last commit
today
healthy
Star history
Issues
66% closed
2,110
open
4,078
closed
+7 / -1
opened / closed, last 4 weeks
Opened vs closed, last 12 weeks
Commits, last 26 weeks
868 commits, active 26 of 26 weeks
214 contributors since Aug 2013
Languages
- Java 91.7%
- HTML 5.8%
- Python 0.8%
- Other 1.7%
Updated daily from the GitHub API. Star tracking since Jun 10, 2026.
Website at a glance
languagetool.org
D- score 25
Weak website security headers
Graded by Mozilla HTTP Observatory, tested 1d ago
Inspect this site yourself
Measures the security configuration of the tool's own website, not the privacy of the product itself. A strong tool can still score low here.
LanguageTool alternatives
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TranslateLocally Offline neural machine translation that runs entirely on your device, with a desktop app and browser extension.
LibreTranslate 100% Self-Hosted. No Limits. No Ties to Proprietary Services.
Linguist Linguist is not just another browser extension. It's a full-featured translation system that respects your privacy. Translate offline on your device, use any translation…
SimplyTranslate Mobile Clearweb, Onion, I2P and Lokinet instances are also available for SimplyTranslate.
LanguageTool license, in plain English
LGPL-2.1 Weak copyleft
Closed-source software is allowed to link to this library, but changes to the library itself must be shared under the same license.
Permits
- Commercial use
- Modification
- Distribution
- Private use
Requires
- Disclose source
- Same license (library)
- State changes
- License and copyright notice
Does not provide
- Liability cover
- Warranty
Why it matters: Weak copyleft protects the project's own files: improvements to them stay open, while the code can still sit alongside closed-source software.
Plain-language summary of the project's license, not legal advice. Read the full text for the exact terms.
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