LanguageTool is an AI-based writing assistant that helps individuals and organizations improve the accuracy, clarity, and style of their writing. Its tools check grammar, spelling, punctuation, capitalization, and word choice, while also highlighting redundancies, complex sentences, and opportunities to refine tone. The paraphrasing tool uses AI to rephrase text in styles such as formal, fluent, simple, or concise. LanguageTool supports English and more than 30 other languages and dialects, making it useful for multilingual writing.

Customers can use the editor online or add LanguageTool to their workflow through browser extensions, email add-ons, office plugins, and apps for Windows and macOS. Integrations include Google Docs, Microsoft Word, LibreOffice, and various writing applications. A proofreading API and solutions for businesses are also available, with a focus on consistent brand voice and GDPR-conform services. The free account offers features such as saved texts, a personal dictionary, and writing statistics, while Premium adds unlimited paraphrasing and more advanced suggestions. LanguageTool also provides productivity statistics to help users track errors, suggestions, and language use.