Writing & notes
LanguageTool
Free proofreading for English, German and other European languages
★ 15k
September 2026
LGPL-2.1
Writing & notes
What we checked ourselves
Not copied from the project's own blurb. These are things we opened and verified, with the date.
- 10 Sept 2026We checked that the link to the project still resolves.
- 13 Sept 2026We read the licence text itself (null). No unusual restrictions were stated.
- 30 Aug 2026We read the project's own documentation and found no sign that development has stopped.
Where this sits among the 52 tools we list in Writing & notes
- Works without using a terminal38 of 52
- Commercial use confirmed as allowed39 of 52
- Requires an API key27 that do not →
- Sends your input to the provider11 that do not →
Only 28 of the 52 meet all of the conditions above.
Counted from our own checks: every tool we list is examined against the same criteria.
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.
How it compares
The conditions that decide whether you can actually use it, side by side.
| Tool | Command line | API key | Sends data out | Phone | Commercial use |
|---|---|---|---|---|---|
| LanguageTool (this page) | Not needed | Required | Yes | No | Yes |
| prompts.chat | Not needed | Not needed | Yes | No | With conditions |
| AppFlowy | Not needed | Not needed | No | No | Yes |
| AFFiNE | Not needed | Not needed | Yes | No | Yes |
"Sends data out" means your input is uploaded to someone's server. Pick "No" when the material cannot leave your organisation.