LanguageTool

LanguageTooler

An open-source-rooted grammar and style checker covering 30+ languages — the multilingual alternative to Grammarly, with rules-based precision plus AI rephrasing.

Product preview

Overview

LanguageTool started as an open-source rules engine and grew into the strongest multilingual grammar checker: where Grammarly is English-first with other languages bolted on, LanguageTool treats German, French, Spanish, Portuguese, Dutch, Polish and Japanese as first-class citizens, with thousands of hand-tuned rules per language plus statistical and AI layers on top.

It wins on coverage and privacy: a self-hostable core (the open-source engine powers paid features), a PII-friendly approach to text handling, and extensions that follow you across browser, Word and desktop. The AI rephrasing and tone tools are more basic than Grammarly's generative suite, and English-only depth still favors Grammarly for native-level nuance. For the majority of the world that writes in other languages — or teams that must keep text on their own servers — LanguageTool is the default.

Pros / Cons

Pros

Best multilingual grammar coverage available
Self-hostable open-source core
Follows you across browser, Word, desktop
Privacy-conscious text handling

Cons

English nuance trails Grammarly
AI rewriting is basic compared to generative suites
Style suggestions vary in quality per language

Who it's for

Writing correctly in a second language

Team-wide grammar standards on shared tools

Privacy-sensitive documents kept on own servers

Multilingual organizations and publishers

Bottom line

The grammar checker for everyone who doesn't write in English — and the private option for everyone who does.

Key Features

30+ language support

Rules-based grammar & style

AI-powered rephrasing

Everywhere: browser, Word, desktop

Self-hostable open-source core

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Frequently asked questions

What is LanguageTool?

LanguageTool is a Productivity tool developed by LanguageTooler. The company was founded in 2016 and is headquartered in Nuremberg, Germany. An open-source-rooted grammar and style checker covering 30+ languages — the multilingual alternative to Grammarly, with rules-based precision plus AI rephrasing.