LanguageTool
LanguageTool is open-source proofreading software that checks grammar and style in English, Spanish, French, German and more than 20 other languages.
- GitHub stars
- 15k
- Last commit
- today
- Licence
- LGPL-2.1
- Self-hosted
- Yes
- Hosted version
- Available
LanguageTool is open-source proofreading software that finds grammar and style errors a simple spell checker would miss. It supports English, Spanish, French, German, Portuguese, Polish, Dutch and more than 20 other languages. The core is written in Java and freely available under the LGPL 2.1 or later.
It can be used in several ways. The project documents how to run your own LanguageTool server, an HTTP API for sending text to a server, a public server that can be used over HTTP, and a Java API with Javadoc. Error detection works through rules, and the development overview explains how to contribute new rules for a language.
Community-contributed Docker files are listed for people who want to run a containerized server. Building from source needs Java 17 and Apache Maven, and the README offers a scripted install as well as a shallow clone option to reduce download size, since a complete clone is large. A forum is available for questions.
Key features
- Grammar and style checking
- Support for 25+ languages
- HTTP API for integrations
- Run your own LanguageTool server
- Java API with Javadoc
- Community Docker images
Pricing: A free Basic tier checks up to 2,000 characters per field. Premium raises that to 150,000 and adds extra checks and AI rephrasing; its price is not shown in the page text.
