LanguageTool
LanguageTool checks spelling, grammar and style in more than 30 languages. You can run the open-source checker on your own server so your writing never leaves your hands. The company's own apps and extensions add paid features.
How hard it is to start using it. Easy: install it like a normal app, or use it in your browser. Advanced: you run it on your own server, use the command line, or it is a tool for developers.
Features
Listed in
Run the checker on your own server; no AI rewriting
How to help
AI contributionsNot stated
The project has not said how it feels about AI-written contributions. Maintainers can set this by claiming the listing.