LanguageTool

What it does

Catches grammar and phrasing problems that a plain spell checker misses, across more than thirty languages. A browser extension checks any text field as you type, and add-ins exist for Word and LibreOffice. Coverage is strongest for English and the major European languages: Japanese appears in the language list but returned no suggestions at all when tested against obvious errors, so it should not be relied on for Japanese. Text goes to the vendor's servers unless you host it yourself.

Summary based on the project's own description. The Japanese page has a fuller beginner guide: setup difficulty, what to prepare, and a step-by-step start.

Screenshots & visuals

Before you start

• Setup difficultySome setup needed
• Command lineNot required
• API keyRequired
• Sends data onlineYes

Judged automatically from the project's own metadata. Always confirm on the official page.

LanguageTool FAQ

Is LanguageTool free?

LanguageTool itself is free, but it needs an API key for an external AI service. That service charges separately, though some have a free tier.

Do I need to install anything or write code to use LanguageTool?

You install it like a normal desktop app. No command line involved.

Does LanguageTool work on a phone?

No. It needs a computer.

Can I use LanguageTool commercially?

The licence is LGPL-2.1. Using it commercially is fine, but if you distribute something built on it you may be required to release that under the same licence. Keep it internal, or check before distributing.

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