LanguageTool

LanguageTool checks text for spelling, grammar, punctuation, casing and style errors. It detects the language you write in and supports more than 30 languages and dialects, including English, German, Spanish, French, Portuguese and Dutch. An AI paraphrasing tool rewrites sentences to be more formal, fluent, simple or concise.

It runs in the online editor, as browser add-ons (Chrome, Edge, Firefox, Opera, Safari), as desktop apps for macOS and Windows, and as add-ons for Google Docs, Microsoft Word, LibreOffice, Gmail, Outlook, Apple Mail and Thunderbird. A paid Proofreading API is offered for developers; its servers are in Germany.

The basic checker is free. Premium adds more than 20,000 extra checks for seven languages, texts up to 150,000 characters, unlimited paraphrasing and a style guide. A Teams plan adds user management and a shared dictionary.

The core is open source under LGPL 2.1 or later. You can run your own local server; AI-based rules are only available in the cloud.

Made for

People who write in one or several languages and want error-free texts, from students and professional writers to teams and businesses that need a consistent brand voice, plus developers who add proofreading to their own software.

Use cases

• Check emails and documents for spelling and grammar errors
• Fix punctuation and casing mistakes
• Rephrase sentences to be more formal or concise
• Check texts in several languages with automatic language detection
• Keep a team's wording consistent with a shared style guide
• Add proofreading to an app through the HTTP API

An alternative to

• Grammarly

  Its core is open source under LGPL 2.1 or later, and you can run your own LanguageTool server; Grammarly is not open source.

• Quillbot

  Open-source core (LGPL 2.1 or later) that also runs on Linux, and a paid Proofreading API for developers.

• Hemingway Editor

  The free basic checker covers spelling, grammar and punctuation in more than 30 languages; Hemingway's grammar fixes are part of the paid Editor Plus.

Alternatives to LanguageTool 3

Writing & Content

Grammarly

AI writing assistant that checks, rewrites and drafts text in apps and websites

FreemiumWebiOSAndroidMacWindowsBrowser extensionAPI / CLI

Has a keyboard app for iPhone, iPad and Android and its own Docs editor; LanguageTool lists no mobile app.

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Writing & Content

Hemingway Editor

Writing editor that highlights hard-to-read sentences and scores readability

FreemiumWebMacWindows

Gives a readability grade level and highlights hard-to-read sentences, adverbs and passive voice as you write.

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Writing & Content

Quillbot

AI writing tools: paraphraser, grammar checker, AI detector, summarizer and more

FreemiumWebiOSAndroidMacWindowsBrowser extension

Includes an AI Detector, a Plagiarism Checker, a Summarizer and a Citation Generator, and has apps for iOS and Android.

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