European grammar checkers: who really owns them, and where your text goes

LanguageTool is published by LanguageTooler GmbH in Hamburg, and nearly every "European Grammarly alternative" list puts it first. What those lists leave out: in 2023 the company was bought by Learneo, a US group that also owns QuillBot. The entity you sign with is German. The owner is American.

What it does well. It checks many languages, runs in your browser, Word and Google Docs, and its core is open source. That last point matters: an IT team can host the core on its own servers and keep every text in-house. The AI rules of the Premium plan are not part of that open-source version.

Free vs Premium. The free plan checks up to 2,000 characters per field and gives you 3 AI rephrasings a day. Premium raises the limit to 150,000 characters. The price only appears at checkout, and it changes with your country: one Swiss user worked out he was paying 51 to 74% more than users in France or Germany.

The catch. User reviews keep pointing at slow support and average value for money. And if your procurement policy asks for European ownership, not just a European address, LanguageTool fails that test.

Tip: for sensitive documents, ask IT to run the open-source core on an internal server. You lose the style suggestions, but nothing leaves the company.

Best for people who write in several languages and want a checker everywhere in the browser. Not for buyers who need European ownership.

DeepL Write comes from DeepL SE, the German translation company based in Cologne. It isn't a rule-based checker like LanguageTool or ProLexis. It's an AI that rewrites your sentence to make it clearer, fixing mistakes along the way. It covers English, German, French, Italian, Portuguese and Spanish.

Price. There's a free version. Write Pro is an add-on at €6.99 per user per month, VAT included, billed yearly, on top of the DeepL Pro Individual or Team plans; it's included in Business. On Pro, DeepL deletes your texts after processing and doesn't use them to train its models. The free version doesn't come with that promise, so keep confidential text out of it.

The catch. An AI that rewrites can shift the meaning of a sentence or flatten your voice. When every change has to be justified by a rule (a contract, a legal brief, a book), a classic checker is safer.

Tip: if your team already pays for DeepL Pro to translate, Write Pro is the cheapest upgrade on this page for better writing.

Best for teams who write in several languages and want smoother text. Not for proofreading where every word must stay the author's.

ProLexis is made by Diagonal, a French software publisher, and it's what proofreaders and publishing houses in France use. It ships with two analyzers: French (703,000 word forms) and US and UK English (580,000), with checks on typography, syntax, meaning and style. The Myriade dictionaries come bundled.

Where it stands out is integration. Beyond Word, LibreOffice, Pages and Keynote, it plugs into InDesign, Illustrator and QuarkXPress, the layout tools publishers live in. It runs on Windows 8 to 11 and macOS 10.12 to 15, Intel and Apple M1 to M4. Diagonal says data is hosted in France.

Price. One plan: €240 a year before VAT, a 12-month subscription you can cancel. Since 2024 there are no lifetime licenses, and old perpetual licenses no longer work. A demo is available on request, and a web service for companies is quoted separately.

What translators say. In a long-running translators' forum thread, ProLexis wins on raw correction speed and accuracy, while Antidote wins on dictionaries. It also handles hyphenation, which matters in layout.

The catch. No browser extension: it checks documents, not what you type in a web form. And it only covers French and English.

Best for translators, editors and comms teams who produce French and English documents. Not for quick checks in the browser.

Scribens is a free, ad-supported online checker for French and English. You don't need an account, and there's a mobile app and a Google Docs add-on.

Who's behind it? The App Store lists the seller as "Scribens", with an address in Montpellier, France. The website says little about the company and nothing about where your text is processed. Fine for a personal note, not for a confidential file.

Limits. Advanced checking only covers the first 6,000 characters of a text, roughly a page and a half. Premium removes ads and lifts the limits, but its price isn't shown before checkout, and the limits it advertises contradict each other (5 million characters a month in the FAQ, 200,000 in the comparison table).

Tip: paste long documents in chunks under 6,000 characters to keep the detailed check on every part, for free.

Best for students and individuals who want a quick check with nothing to install. Not for companies that need to know who processes their data.

Grammalecte is an open-source grammar checker for French, under the GPL 3 license. Early in 2026 the project was taken over by Algoo, a French open-source software company; version 2.3.0 shipped at the end of 2025.

Its selling point is rare: all analysis runs on your computer. The official site says it plainly: no text is sent anywhere. It works in LibreOffice and OpenOffice, Firefox, Thunderbird, Chrome (through the Firefox extension), ONLYOFFICE, and code editors like Vim, Emacs and Sublime Text. Developers can run it from the command line or as a small Python server.

The catch. It only checks French, and it doesn't rephrase or suggest style changes. There's no company support desk: you rely on the docs and the community.

Tip: if your team already works in ONLYOFFICE, Grammalecte ships there as a plugin, so you get local French checking without installing anything on each laptop. And because it runs as a small Python server, an IT team can host one instance on the internal network and plug it into in-house tools, with no text ever reaching an outside vendor.

Best for anyone writing French text that can't leave the machine: legal, HR, health, research. Not for English writing.

MerciApp is a French company whose checker works in your browser, on emails, messages and work tools. It lists clients such as Orange, PayFit and France TV, and its pricing page says data is hosted in France. It's built for French: use it if your team writes to French-speaking customers.

Price. The free plan gives you 600 analyzed words and 3 rewrites a day. Assist costs €24 a month, or €144 a year before VAT (€12 a month). Enterprise is quoted and adds SSO and team management. The trial lasts 30 days with no card.

The catch. Users complain about correct words flagged as errors, billing mistakes and slow support, and the best-known review platform suspended MerciApp's rating over misleading use of its content.

Tip: run the 30-day trial (no card needed) on the team that sends the most French emails before you buy seats, and if you do buy, take the annual plan: it works out at €12 a month instead of €24. MerciApp also runs a partnership with ProLexis, which is worth asking about if your marketing team writes short messages while your publishing team proofreads long documents.

Best for sales and support teams writing short messages in French. Not for proofreading long documents.