How to Check German Grammar on a Mac — in Any App, Without Copy-Paste

If you write German on a Mac, you probably know the ritual. You draft an email in Mail or a message in Slack, hesitate over a comma before dass, second-guess whether it should be bei sie or bei Ihnen, and then copy the whole thing into a browser tab to check it. LanguageTool, Duden Mentor, some AI chatbot — paste, wait, fix, copy back. It works, but it turns every German paragraph into a three-app round trip.

That workflow exists because a real German grammar checker for Mac has always been hard to find. macOS ships decent English tools, and the best German checkers live on the web. This guide looks at what your Mac can actually do for German out of the box, where the web checkers fall short in 2026, and how to check German grammar system-wide — in any app, with one keyboard shortcut. If you want a broader look at the tools themselves rather than the Mac workflow, start with our main guide to German grammar checkers; this post is about making German correction work everywhere on your Mac.

What macOS gives you out of the box

Apple ships every Mac with system-wide spellcheck, and it does support German. Set the language under System Settings → Keyboard → Text Input, or per-document via Edit → Spelling and Grammar, and misspelled German words get the familiar red underline in Mail, Notes, Pages, and TextEdit.

Here is the honest part: for German, that is essentially where it ends.

• Spelling only. macOS catches Nachrict instead of Nachricht, but the actual grammar-checking layer in macOS is built for English. Write „Ich helfe den Kunde“ and nothing happens — every word is spelled correctly, the case is just wrong.
• No comma help. German comma rules are strict and grammatical („Ich hoffe dass es klappt“ is missing a mandatory comma before dass). The system checker will not flag it.
• No Groß- und Kleinschreibung. Lowercase nouns — the most common German typing mistake on a fast keyboard — sail straight through whenever the lowercase form happens to be a valid word.

Microsoft Word for Mac does bundle a German grammar module that goes further, but it only works inside Word. The moment you switch to Mail, Slack, Teams, or a browser, you are back to red-underline spellcheck at best.

The web checkers: good German, awkward workflow

The two big names in German checking are genuinely good at German — that deserves saying clearly.

LanguageTool

LanguageTool was built by a German team and its German rule set is excellent: Kasus, comma placement, capitalization, style. The catch in 2026 is access. As of February 2026, LanguageTool made its browser extension Premium-only, and the free web checker is capped at 10,000 characters, with the more advanced rules (style, punctuation refinements, picky mode) behind the paywall. Full coverage means a subscription — and outside the supported integrations you are still pasting text into a window. We compare the options in more depth in our guide to LanguageTool alternatives for Mac.

Duden Mentor

Duden is the authority on German orthography, and Duden Mentor reflects that: its corrections track the official rules closely. But the free tier checks only 1,500 characters at a time, with ads — roughly half a page. Premium raises the limit to 100,000 characters and adds a monthly quota of AI-assisted rewrites, on a recurring subscription. And again: it is a website plus browser extensions. Your German email in Mail still has to travel to a browser tab and back.

Both tools share the same structural problem for Mac users: the checker lives somewhere your writing doesn’t. Every check costs a copy, a tab switch, a paste, and a paste back — and for anything confidential, it also means sending your text to a cloud server.

Check German grammar in any Mac app: WunderType

WunderType takes the opposite approach. Instead of bringing your text to the checker, it brings the checker to your text — via the macOS Accessibility API, so it works in effectively any app.

The whole workflow:

• Select German text anywhere — Mail, Word, Slack, Safari, WhatsApp, your CMS.
• Press your keyboard shortcut (for example ⌘⇧G for Correct Grammar).
• The corrected text replaces your selection, in place. No browser tab, no clipboard juggling.

The Correct Grammar mode works in whatever language the text is in, and modern AI models are genuinely strong at German grammar — the classic trouble spots included:

• Kasus: „wir melden uns morgen bei sie“ → „wir melden uns morgen bei Ihnen“ — the dative after bei, plus the polite form.
• Kommasetzung: „Ich denke dass wir das Angebot annehmen sollten“ → „Ich denke, dass wir das Angebot annehmen sollten.“
• Groß- und Kleinschreibung: „vielen dank für ihre nachricht“ → „Vielen Dank für Ihre Nachricht“ — nouns capitalized, ihre corrected to the formal Ihre.

Beyond the five built-in modes, you can create unlimited custom prompts with their own shortcuts. A useful setup for German writers: a dedicated prompt like „Korrigiere deutsche Grammatik, Rechtschreibung und Kommasetzung. Behalte den Ton bei.“ bound to its own hotkey — effectively a purpose-built German proofreader available in every app. You can add another prompt that turns English drafts into clean German; if that is your use case, see our guide to translating English to German with correct grammar.

Where the German text goes (or doesn’t)

WunderType 1.5 supports four AI providers, and two of them keep your German text entirely on your Mac: On-Device AI runs local models via Apple’s MLX framework directly inside the app, and Ollama connects to local models you manage yourself. Choose either, and your contracts, client emails, or internal documents are corrected without a single byte leaving the machine — a hard requirement for many teams in Germany. If you prefer frontier cloud models, you can instead plug in your own OpenAI or OpenRouter key, stored in the macOS Keychain and called directly with no middleman server. The app itself collects nothing: no accounts, no analytics, no telemetry, no clipboard monitoring, and it runs in the App Sandbox. More on that setup in our overview of local AI writing tools for Mac.

Comparison: checking German on a Mac in 2026

Tool	Where it works	German depth	Pricing	Privacy
macOS built-in	Most native apps	Spelling only; no grammar, Kasus, or commas	Free	On-device
LanguageTool	Website; extension and integrations now Premium-only	Excellent rules for Kasus, Kommas, style	Free web check (10,000 chars, basic rules); subscription for full features	Cloud processing
Duden Mentor	Website + browser extension	Authoritative Duden rules	Free up to 1,500 chars with ads; Premium subscription	Cloud processing
Microsoft Word	Word documents only	Solid German grammar module	Microsoft 365 subscription	Depends on cloud settings
WunderType	Any Mac app, via shortcut	AI-based: Kasus, Kommasetzung, Groß-/Kleinschreibung, tone	$8.99 one-time	Fully local option (MLX/Ollama); zero telemetry

Is there a German version of Grammarly?

Not from Grammarly itself — Grammarly remains English-only, which is why this question keeps coming up in every German writing forum. The closest equivalents are LanguageTool and Duden Mentor for rule-based checking in a browser, or WunderType if you want a German grammar checker for Mac that gives you the Grammarly-style “fix it where I’m typing” experience across the whole system. The practical difference: Grammarly injects itself into text fields and continuously reads what you type, while WunderType only ever touches text you explicitly select and correct — a model that suits German privacy expectations rather better.

How do I turn on grammar checking on my Mac?

For the built-in checker: in most Apple apps, choose Edit → Spelling and Grammar → Check Grammar With Spelling. Just be aware that this toggle adds English grammar rules — for German text you still only get spellcheck, as covered above. Our general guide to grammar checking on a Mac walks through the system settings step by step; for German grammar you will need a dedicated tool on top.

Verdict

If you write German occasionally and don’t mind the browser round trip, LanguageTool’s free web checker is still a fine place to paste a paragraph. If you need authoritative Duden rulings on tricky orthography, Duden Mentor Premium earns its keep. But if German is part of your daily work on a Mac — emails, docs, chat, support tickets — the copy-paste loop is the real cost, and no website fixes that.

A German grammar checker for Mac should work where you write: select the sentence, hit the shortcut, keep going. WunderType does exactly that in every app, handles Kasus, Kommas and Groß-/Kleinschreibung with modern AI models, can run fully offline on local models, and costs $8.99 once instead of a subscription forever.

Download WunderType from the Mac App Store and correct your next German email without leaving Mail.