LanguageTool
Open-source proofreading software that detects grammar, style, and spelling errors in 20+ languages. More advanced than simple spell checkers.
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Open-source proofreading tool that catches grammar & style errors more deeply than spell checkers. Supports 20+ languages.
Core Features
- Checks grammar, spelling, punctuation, style, and consistency
- Supports 20+ languages (English, Spanish, French, German, etc.)
- Multiple interfaces: desktop app, browser extension, HTTP API, Java API
- Extensible with custom rules
- Docker deployment available
What It Can't Do
- •First launch downloads dictionary files (~200MB), needs internet. 2. Limited support for CJK languages; mainly for Western languages. 3. For self-hosted server, use community Docker images and ensure Java is configured. 4. Custom rules require XML knowledge.
Use Cases
- Proofreading for students, writers, and professionals
- Content quality assurance for editors and translators
- Integration into custom writing tools or CMS via API
Detailed Introduction
LanguageTool is an open-source proofreading tool that goes beyond basic spell checking. It finds grammar mistakes, style issues, punctuation errors, and even checks for consistency in over 20 languages including English, Spanish, French, German, Portuguese, Polish, Dutch, and more. It can be used as a desktop application, a browser extension, or integrated into your own software via a public HTTP API or Java API. The core is licensed under LGPL 2.1+, making it free for personal and commercial use. Community Docker images are available for easy server deployment. It also supports rule-based error detection that can be extended with custom rules.
Troubleshooting & FAQ (1)
TroubleshootingWhy does LanguageTool change typographic apostrophe to straight apostrophe when capitalizing sentences in Catalan?
The UPPERCASE_SENTENCE_START rule in LanguageTool now preserves the original apostrophe character. If the original sentence contains a typographic apostrophe (’), the suggested correction will use the same typographic apostrophe instead of normalizing to a straight apostrophe ('). This fix applies when there is no explicit rule activated for apostrophe type, or when the text already uses typographic apostrophes. Ensure you are using an up-to-date version of LanguageTool.
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Getting Started
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Download desktop app from https://languagetool.org for your OS
Install and launch the application
Paste or type text into the window; errors are highlighted with suggestions
- Download desktop app from https://languagetool.org for your OS
- Install and launch the application
- Paste or type text into the window; errors are highlighted with suggestions
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Open Source Transparency
View GitHub SourceUninstall Info
Windows: Control Panel > Programs > Uninstall LanguageTool; macOS: drag app to Trash; Linux: use package manager. Browser extensions can be removed from extension management page.
No Extra Dependencies
Ready to use after download. No additional runtime required.
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