LanguageTool is a free online proofreading service that helps you check your text for grammar and spelling mistakes in over 30 languages. It offers a wide range of features for both casual and professional use, such as an AI-based grammar checker, a personal dictionary, quality scoring for texts, and more.

It includes browser add-ons for Chrome, Edge, Firefox, Safari, and Opera, as well as Office plugins for Google Docs, Word, OpenOffice, and LibreOffice.

It also offers desktop apps for macOS and Windows, E-Mail add-ons for Gmail, Outlook, Apple Mail, and Thunderbird, and Editor Apps for iOS, macOS, and Windows.

Premium users also have access to a rephrasing tool, Picky Mode for advanced punctuation, and style, and typography suggestions. LanguageTool is trusted by organizations such as BMW Group, Amazon, RingCentral, European Union, Spiegel Magazine, Deutsche Presse-Agentur (dpa), Heise, Bertelsmann Stiftung, Schweizer Radio und Fernsehen (SRF), JetBrains, IP Australia, and Wirtschaftsuniversität Wien.

It is free to use and also offers a 20% discount for its Premium version.