5 Best German Grammar Checkers in 2026

Why German Grammar Checking Is Hard

Most grammar checkers were designed for English first. German presents a fundamentally different set of challenges that many tools struggle with:

• Four grammatical cases — Nominativ, Akkusativ, Dativ, and Genitiv each change article forms and adjective endings. "Ich gebe dem Mann" vs. "Ich sehe den Mann" is the kind of mistake a checker must catch.
• Three genders — Every noun is der, die, or das. There's no reliable rule — you have to know that it's das Mädchen (neuter), not die Mädchen, even though Mädchen means "girl."
• Compound words — German famously glues words together. "Donaudampfschifffahrtsgesellschaft" is a valid word. A checker needs a huge vocabulary to avoid flagging legitimate compounds as typos.
• Flexible word order — The verb goes to the end in subordinate clauses ("weil ich nach Hause gehe"), and separable prefix verbs split apart ("Ich rufe dich morgen an"). Simple pattern-matching doesn't cut it.
• Neue Rechtschreibung — German spelling was reformed in 1996 and updated again in 2006. Good tools must recognize both old and new spellings and suggest the current standard.

5 Best German Grammar Checkers

1. LanguageTool — Best Free German Grammar Checker

LanguageTool was originally developed at a German university, and it shows. German is one of its best-supported languages with thousands of grammar, style, and punctuation rules.

• German accuracy: Excellent — catches case errors, gender mismatches, comma rules (which are mandatory in German, unlike English), and Rechtschreibung issues
• How it works: Browser extension (Chrome, Firefox, Safari, Edge), web editor, LibreOffice/Word add-on
• Price: Free (limited checks) or €5/month for premium with longer texts and style suggestions
• Open source: You can self-host it for full privacy

Limitation: The browser extension works well, but there's no true system-wide integration on macOS. You can't use it in native Mac apps like Mail or Notes without copying text.

2. Duden Mentor — Best for Native German Speakers

Duden Mentor is built by Duden, the definitive authority on German spelling and grammar since 1880. If anyone should get German right, it's Duden.

• German accuracy: Very strong — especially for style, comma placement, and Rechtschreibung
• How it works: Web editor, browser extension, Word add-in
• Price: Free tier checks up to 800 characters. Premium starts at €7/month.
• Unique: Style suggestions follow Duden's own editorial guidelines

Limitation: German-only — no English or other languages. The free tier's 800-character limit is restrictive. No Mac desktop app.

3. Grammarly — Limited German Support

Grammarly is the most popular grammar checker globally, but its German support remains limited. It can detect some German spelling errors and basic grammar issues, but it doesn't reliably catch case errors, gender mismatches, or comma rules.

• German accuracy: Basic — catches obvious spelling errors but misses most grammar issues
• How it works: Browser extension, Mac desktop app, mobile keyboard
• Price: Free (basic) or $12/month (premium)
• Strength: If you write in both English and German, the English side is excellent

Limitation: Not recommended as a primary German grammar checker. It was designed for English and the German support feels like an afterthought.

4. FlowWrite — Best for Mac Users Writing in German

FlowWrite is a macOS menu bar app that works in every application. Select text, press Tab, and the AI corrects your German grammar in place — whether you're in Mail, Slack, VS Code, or any other app.

• German accuracy: Very good — AI-powered correction handles cases, gender, compound words, and comma rules
• How it works: System-wide on macOS. Works in every app with text input, not just browsers.
• Price: Free (10 corrections/day) or $2.99/month for 1,000 corrections/day
• Multilingual: Handles German and English seamlessly — perfect for bilingual writers who switch between languages in the same email

Limitation: macOS only. No Windows or web version. Requires the Accessibility permission.

5. DeepL Write — Best for Rewriting German Text

DeepL Write comes from the team behind DeepL Translator. It's excellent at improving German text — rephrasing awkward sentences, fixing grammar, and suggesting more natural wording.

• German accuracy: Good for rewrites, but it changes more than just grammar — it often restructures sentences entirely
• How it works: Web editor, browser extension
• Price: Free (limited) or included with DeepL Pro ($9/month)
• Strength: Particularly good at making translated text sound more natural in German

Limitation: Not a traditional grammar checker. It rewrites rather than corrects, so you lose control over your original phrasing. No real-time checking as you type.

Comparison Table

Best for Mac Users

If you use a Mac and write in German regularly, you've probably noticed the gap: most German grammar tools are browser extensions. They work in Google Docs, but not in Mail.app. They work in web forms, but not in Slack or VS Code. You end up copying text back and forth.

FlowWrite solves this by working at the system level. It intercepts your text in any app — native or web-based — and corrects German grammar in place. For bilingual writers who switch between German and English throughout the day, this is a significant workflow improvement.

The AI handles both languages without needing to switch modes. Write a German email in Mail, correct it with one keystroke. Switch to Slack and reply in English — same keystroke, same tool.