LanguageTool is a writing assistant covering grammar, spelling, style and tone, with a paraphrasing tool alongside the checker.
Its distinguishing strength is language coverage. Most competitors are English-first with other languages as an afterthought; LanguageTool has treated multilingual checking as the core problem from the start, which matters if you write in German, French, Spanish or Dutch as well as English. Tone guidance sits alongside correctness – finding the right register rather than only the right grammar.
The core is open source, which is a genuine differentiator: self-hosting is possible for organisations that cannot send draft text to a third party, and the checking logic is inspectable. A free tier covers everyday use, with Premium and a business plan above it. Editor, browser extensions and app integrations cover the usual writing surfaces.
