How we review: this assessment is based on the product’s official documentation, current pricing and published independent evaluations; it is not a hands-on test. Read our review methodology.
LanguageTool has long been the grammar checker people recommend when the question is “what about languages other than English?”. It grew out of an open-source project, and its core engine is still open source. In 2026, though, it made a significant change: its browser extension — the way most people used it — is now available only to Premium subscribers. This review assesses LanguageTool as described on its official website, help center and announcement pages.
What it is
LanguageTool is a grammar, spelling, punctuation and style checker with AI-assisted rewriting. LanguageTool says it supports more than 30 languages and dialects, with English (in six regional variants), Spanish, German, French, Dutch and Portuguese as its main languages. It runs on its website, as browser extensions, as add-ins for email clients and word processors, as desktop apps for Windows and macOS, on iOS, and through a developer API. See our LanguageTool directory entry for a short summary.
Key features
- Multilingual checking. Grammar, spelling and punctuation checks across its supported languages, with Premium adding more than 20,000 additional checks for English, German, French, Spanish, Dutch, Polish and Portuguese.
- Paraphraser. AI rewriting that makes sentences more formal, fluent, simple or concise.
- Synonyms and dictionary. Double-click synonyms and a personal dictionary.
- Style Guide. Custom style rules on Premium, plus a shared Team Style Guide and Team Dictionary on team plans.
- Integrations. Chrome, Edge, Firefox, Opera and Safari; Gmail, Outlook (beta), Apple Mail and Thunderbird; Google Docs, Word, Apple Pages and LibreOffice.
- API and open source. A proofreading API with servers in Germany and texts that are not stored, and an open-source core under LGPL 2.1 that developers can run on their own server.
Pricing
At the time of writing (October 2026), LanguageTool’s help center lists these individual Premium prices:
| Billing | Price |
|---|---|
| Monthly | €19.90 a month |
| Quarterly | €39.90 (€13.30 a month) |
| Annual | €59.89 a year (€4.90 a month) |
| Two years | €99.90 (€4.16 a month) |
Team subscriptions are priced per user per year — the help center gives €56.90 per user for teams of up to 20 — and subscriptions renew automatically. The free plan allows 2,000 characters per text field and three AI sentence rephrasings a day; Premium raises the limit to 150,000 characters with unlimited paraphrasing. LanguageTool advertises a 14-day money-back guarantee on Premium, and the pricing page was not displaying its prices correctly when we checked, so confirm figures at checkout.
Strengths
Multilingual support is the reason to choose LanguageTool. Many writing assistants are excellent in English and limited elsewhere; LanguageTool’s depth in German, French, Spanish, Dutch, Portuguese and Polish makes it a natural fit for people who switch languages during the day. Our checklist for choosing an AI writing assistant puts language coverage near the top for this reason.
Annual Premium is inexpensive. At under €5 a month on annual billing, and less on a two-year plan, it is one of the cheaper paid writing assistants.
The open-source core is a genuine differentiator. Developers and organizations can run their own LanguageTool server, and LanguageTool says the browser extension will continue to work as before for users connected to their own server — useful for teams with strict data-handling rules.
Privacy messaging is clear. The API’s servers are in Germany, LanguageTool describes the service as GDPR-compliant, and texts sent to the API are not stored. The company also states that advertising or selling user data would conflict with its values.
Limitations
The extension paywall changes the value proposition. LanguageTool’s announcement explains that generative AI has raised costs and that most of its roughly six million extension users were on the free plan. After a 14-day trial, free users’ extensions stop underlining errors and lose paraphrasing and synonyms; free use continues only on the website. Some older LanguageTool pages still describe a free extension, which adds confusion. The company points free users to its sister brand QuillBot’s free extension instead.
The free plan is now a sampler. With 2,000 characters per check and three AI rephrasings a day, and no in-browser checking, it is useful for occasional checks rather than everyday writing.
Monthly billing is expensive. At €19.90, a single month costs about a third of a full year on annual billing.
Generative features are modest. Rephrasing and synonyms are useful, but LanguageTool is primarily a checker; people who want drafting, summarizing or tone transformation will find more in general assistants.
Who it’s for
- Multilingual writers working in several European languages.
- Budget-conscious professionals willing to commit to annual billing.
- Organizations and developers that want a self-hosted or privacy-focused checker.
- Teams needing shared style guides and dictionaries.
Alternatives
- Grammarly — stronger generative and team features, focused on English.
- QuillBot — LanguageTool’s sister brand, with a free extension and a paraphrasing focus.
- DeepL Write — writing improvement from the DeepL translation team.
Verdict
LanguageTool earns 3.5 out of 5. Its documented strengths — deep multilingual checking, an open-source and self-hostable core, clear privacy commitments and inexpensive annual Premium — still make it one of the best choices for people who write in more than one language. We deduct a point and a half because the browser extension is now Premium-only, the free plan has become a narrow website sampler, and monthly billing is poor value compared with annual plans.
