Duden-Mentor

Free plan APIExtensionMacWebWindows

What Duden-Mentor is

Duden-Mentor checks German writing for spelling, grammar and punctuation, then suggests corrections and style improvements. It can point out filler words, repetition and sentences that are too long, with suggestions to make text clearer and easier to read. Writers can choose 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 such as Gmail, Web.de, GMX.de, Trello, Facebook and WordPress. A Microsoft Word add-in supports macOS from Word 2016 and Windows from Word 2019. An internet connection is required. Duden says text is encrypted in transit, is not used for AI training and is deleted after checking. The Basis plan is free and includes 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, with different monthly correction or optimization limits.

Who it suits

It suits people writing in German who want spelling, grammar, punctuation and style suggestions in a browser or supported version of Word. Its regional variants may be useful to writers working for readers in Germany, Austria or Switzerland.

What it does well

Checks spelling, grammar, punctuation and style
Supports German variants for three countries
Browser extensions cover Chrome, Firefox and Edge
Works in text fields on several listed services
Free Basis plan is available

What to know first

Checks German texts only
Requires an internet connection
No desktop or mobile app
Paid plans are billed annually

Limits

Basis includes 10 words in a personal dictionary and up to 500 characters without an account. Pur includes 10 test corrections or rewrites per month, while Premium includes 250 monthly text optimizations; Premium Plus lists unlimited monthly optimizations.

Plans

Plan	Billed and limits	Price
Basis	0 € / Monat · basic functions · personal bookmark with registration	Free
Pur	35,88 € pro Jahr; jährliche Zahlweise, jährlich kündbar · 10 Test-Korrekturen/Umformulierungen pro Monat	€2.99 a month
Duden Pur	35,88 € per year, annual payment and annual cancellation · ad- and tracking-free duden.de and app · personal bookmark	€2.99 a month
Premium	95,40 € per year, annual payment and annual cancellation · 250 text optimizations per month · selectable text type and style · Word add-in · Chrome, Firefox and Edge extensions · style tips · synonyms	€7.95 a month
Premium Plus	119,40 € per year, annual payment and annual cancellation · unlimited text optimizations per month · selectable text type and style · Word add-in · Chrome, Firefox and Edge extensions · style tips · synonyms	€9.95 a month

As mentor.duden.de lists them, read 20 Oct 2026. The maker's own page has the final word.

Getting started

Visit the Duden-Mentor website.
Start with the free Basis plan or choose a paid plan.
For browser use, choose the extension for Chrome, Firefox or Microsoft Edge.
For Word use, use the add-in on supported macOS or Windows versions.
Connect to the internet to check text.

Verdict

Duden-Mentor combines German proofreading with style suggestions across browser text fields and supported Word versions. Check the plan limits and annual billing details to see whether its free or paid option fits your writing needs.

Questions

Is Duden-Mentor free?

Yes. Basis is listed as free. It includes 10 words in a personal dictionary and 500 characters without an account.

What do the paid plans cost?

Pur is €2.99 a month, billed 35,88 € per year; Premium is €7.95 a month, billed 95,40 € per year; and Premium Plus is €9.95 a month, billed 119,40 € per year. Each is billed annually and can be canceled annually.

Which platforms and browsers does it support?

It is available on the web, macOS and Windows, with browser extensions for Chrome, Firefox and Microsoft Edge. It also offers a Word add-in for macOS Word 2016 and later, and Windows Word 2019 and later.

Does Duden-Mentor check languages other than German?

No. The service checks German texts, with variants for Germany, Austria and Switzerland.

Who makes Duden-Mentor?

Duden-Mentor is from Duden, a brand of the Cornelsen Group.

Does Duden-Mentor offer a free trial?

Yes, a free trial is listed.

Facts from Duden-Mentor's own pages

API authentication: API access uses an x-api-key header and developers request keys by emailing Duden. · api.duden.io, 20 Oct 2026
API delivery: API v2 returns a correlation ID immediately and posts the processed result to a publicly reachable HTTPS callback URL. · api.duden.io, 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. · api.duden.io, 20 Oct 2026
API versions: The public correction API provides v1 for spellchecking and synonyms and v2 for asynchronous AI correction and paraphrasing. · api.duden.io, 20 Oct 2026
Browser extension: Yes · mentor.duden.de, 20 Sept 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. · mentor.duden.de, 20 Oct 2026
Browser support: Browser extensions are available for Chrome, Firefox and Microsoft Edge. · mentor.duden.de, 11 Oct 2026
Business licensing: Business plans use annual per-user licenses, and prices for more than 25 licenses are available on request. · lp.mentor.duden.de, 11 Oct 2026
Company relationship: Duden is a brand of Cornelsen Group and the Duden-Mentor Word add-in is supplied by Cornelsen Verlag GmbH. · linkedin.com, 20 Oct 2026
Company size: LinkedIn lists Duden in the 11–50 employee range and places its headquarters in Berlin. · linkedin.com, 20 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. · lp.mentor.duden.de, 11 Oct 2026
Desktop app: No · mentor.duden.de, 20 Sept 2026
Founded: Cornelsen states that Franz Cornelsen founded the Cornelsen Verlag in Berlin in 1946. · cornelsen.de, 20 Oct 2026
Free plan: Yes · mentor.duden.de, 20 Sept 2026
Grammar: It checks German grammar and displays correction suggestions beneath the text. · mentor.duden.de, 20 Oct 2026
Integrations: The Word add-in supports Microsoft Word for macOS from version 2016 and Windows from version 2019. · mentor.duden.de, 11 Oct 2026
Languages: The service checks German texts only. · lp.mentor.duden.de, 11 Oct 2026
Limit: comma accuracy: An independent test reports that the tool sometimes removes useful commas or inserts commas in unsuitable positions. · dkeu.de, 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. · campuslektor.com, 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. · de.trustpilot.com, 20 Oct 2026
Limit: reliability: Independent reports mention disappearing text, maintenance downtime and browser-extension sessions repeatedly logging users out. · dkeu.de, 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. · christianwoellecke.de, 20 Oct 2026
Maker: Duden is a brand of the Cornelsen Group. · duden.de, 11 Oct 2026

Where Duden-Mentor stands on Freedom251

Online Dictionaries#4 of 39
Grammar checkers#12 of 88