languagetool
by languagetool-org
LanguageTool is open-source proofreading software that checks grammar, spelling and style in English, Spanish, French, German and more than 20 other languages. It can run as a desktop app, a command-line tool or your own web server for checking text.
- Stars
- 15.2k
- Licence
- LGPL-2.1
- Runs on
- A small server
- Setup
- Moderate
- Language
- Java
- Age
- 4830 days
What you can do with it
- Proofread emails, web copy and documents for grammar, spelling and style mistakes
- Run your own private grammar-checking server that other apps can call over HTTP
- Check text in more than 25 languages from the command line or a desktop window
Make money with it
A freelancer could offer proofreading and editing services in several languages, using LanguageTool to speed up the first pass.
An idea, not financial advice. Check the licence before charging for anything built on it.
Ways a business could use it
- Proofread customer-facing copy, newsletters and proposals in-house without paying for a per-seat writing subscription
- Offer multilingual proofreading or content editing to clients, using a self-hosted checker to keep their text private
Can you use it commercially?
Usable in paid products, but changes to its own files must be shared under the same licence.
Not legal advice. Read the project's licence file before building a product on it.
Getting it running
Install with the provided install.sh script, build from source with Java 17 and Maven, or use a community-made Docker image to run your own server.
Follow the official instructions in the project README.
Things to check
- The README's Docker images are community-made rather than official
- Rule-based checking is less capable than the premium features of the company's paid service
- Installer script asks you to pipe a download into sudo bash, so review it first
Who's talking about it
Checked 29 Oct 2026. Summary drafted by AI from the project's README.
