Duden-Mentor
Duden-Mentor checks German text for spelling, grammar, punctuation and style, and suggests corrections.
What Duden-Mentor is
Duden-Mentor checks German text for spelling, grammar, punctuation and style, and suggests corrections. It can flag filler and repeated words as well as overly long sentences, with suggestions intended to improve readability. Users can select writing variants for Germany, Austria or Switzerland; the service checks German only. Browser extensions are available for Chrome, Firefox and Microsoft Edge, and the plug-in works in text fields on services including Gmail, Web.de, GMX.de, Trello, Facebook and WordPress. A Word add-in supports macOS from Word 2016 and Windows from Word 2019. An internet connection is required. Duden says texts are encrypted in transit, not used to train AI and deleted after checking. The Basis plan is free and lists a 10-word personal dictionary and 500 characters without an account. Paid plans are billed annually: Pur is €2.99 a month, Premium is €7.95 a month and Premium Plus is €9.95 a month. Their listed monthly correction or optimization limits differ, while Premium and Premium Plus include browser and Word tools.
Good
- Checks spelling, grammar, punctuation and style.
- Supports German variants for three countries.
- Browser extensions cover Chrome, Firefox and Edge.
- Texts are deleted after checking, according to Duden.
Watch out
- Checks German text only.
- Requires an internet connection.
- Word add-in requires specified Word versions.
- Paid plans use annual billing.
Who it suits
It suits German writers who want spelling, grammar, punctuation and style suggestions, including those writing for Germany, Austria or Switzerland. Browser and Word users can use its listed extensions and add-in, subject to the stated version requirements.
Verdict
Duden-Mentor is focused on German proofreading and style, with browser and Word integrations and regional variants. Compare the annual plans’ listed limits and features against the free Basis option.
Plans and prices
From Duden-Mentor's own pricing page, checked 20 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Basis | Free | basic functions · personal bookmark with registration · 0 € / Monat |
| Duden Pur | €2.99 a month | ad- and tracking-free duden.de and app · personal bookmark · 35,88 € per year, annual payment and annual cancellation |
| Pur | €2.99 a month | 10 Test-Korrekturen/Umformulierungen pro Monat · 35,88 € pro Jahr; jährliche Zahlweise, jährlich kündbar |
| Premium | €7.95 a month | 250 text optimizations per month · selectable text type and style · Word add-in · Chrome, Firefox and Edge extensions · style tips · synonyms · 95,40 € per year, annual payment and annual cancellation |
| Premium Plus | €9.95 a month | unlimited text optimizations per month · selectable text type and style · Word add-in · Chrome, Firefox and Edge extensions · style tips · synonyms · 119,40 € per year, annual payment and annual cancellation |
The facts
Each one read from Duden-Mentor's own pages, with the date it was checked.
What it does
- API authentication
- API access uses an x-api-key header and developers request keys by emailing Duden.checked 20 Oct 2026
- API delivery
- API v2 returns a correlation ID immediately and posts the processed result to a publicly reachable HTTPS callback URL.checked 20 Oct 2026
- API language options
- API v2 accepts german_DE, german_AT and german_CH variants and supports complete-result or sentence-segment callbacks.checked 20 Oct 2026
- API versions
- The public correction API provides v1 for spellchecking and synonyms and v2 for asynchronous AI correction and paraphrasing.checked 20 Oct 2026
- Business licensing
- Business plans use annual per-user licenses, and prices for more than 25 licenses are available on request.checked 11 Oct 2026
- Data hosting
- The business product page states that texts are sent using TLS 1.2 and a 128-bit key to AWS servers contractually located in Frankfurt, Germany.checked 11 Oct 2026
- Grammar
- It checks German grammar and displays correction suggestions beneath the text.checked 20 Oct 2026
- Integrations
- The Word add-in supports Microsoft Word for macOS from version 2016 and Windows from version 2019.checked 11 Oct 2026
- Languages
- The service checks German texts only.checked 11 Oct 2026
- Licence
- The Firefox extension is marked All Rights Reserved, so the product is proprietary rather than open source.checked 20 Oct 2026
- Limit: comma accuracy
- An independent test reports that the tool sometimes removes useful commas or inserts commas in unsuitable positions.checked 20 Oct 2026
- Limit: document workflow
- An academic-focused review says the web editor has no file upload, loses formatting and footnotes when copying from Word, and requires corrections to be accepted individually.checked 20 Oct 2026
- Limit: pricing and contracts
- Trustpilot reviewers complain that advertised monthly prices can result in annual contracts and that the service is expensive compared with alternatives.checked 20 Oct 2026
- Limit: reliability
- Independent reports mention disappearing text, maintenance downtime and browser-extension sessions repeatedly logging users out.checked 20 Oct 2026
- Limit: style overmarking
- A professional reviewer found that many style warnings in a scientific essay targeted word repetition and made the text difficult to assess.checked 20 Oct 2026
Where it runs
- Browser extension
- Yeschecked 20 Sep 2026
- Browser integrations
- Extensions work in Chrome, Firefox and Edge and can insert corrected text into services such as Gmail, WordPress, Trello, Facebook and Twitter.checked 20 Oct 2026
- Browser support
- Browser extensions are available for Chrome, Firefox and Microsoft Edge.checked 11 Oct 2026
- Desktop app
- Nochecked 20 Sep 2026
The company
- Company relationship
- Duden is a brand of Cornelsen Group and the Duden-Mentor Word add-in is supplied by Cornelsen Verlag GmbH.checked 20 Oct 2026
- Company size
- LinkedIn lists Duden in the 11–50 employee range and places its headquarters in Berlin.checked 20 Oct 2026
- Founded
- Cornelsen states that Franz Cornelsen founded the Cornelsen Verlag in Berlin in 1946.checked 20 Oct 2026
- Maker
- Duden is a brand of the Cornelsen Group.checked 11 Oct 2026
Money
- Free plan
- Yeschecked 20 Sep 2026
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