Show HN: I built a small app for FSI German Course

German has around 100 million speakers and is the most widely spoken language in Europe. Whether it's for a job in Berlin, a move to Vienna, or just because you want to actually speak it. It's worth doing right.

You've never heard of the FSI course? That's the point. It's not a consumer product. It's what serious language learners have quietly used for decades because it actually works. We took it, cleaned it up, and built a modern app around it.

No streaks. No bullshit. Just you, native audio, and a proven structure that gets you to real German.

Start Unit 1 for free →Every unit opens with a dialogue broken into build-ups. You hear "good" then "morning" then "Good morning, Mr. Becker." Fragment by fragment until the full sentence clicks. Your ear picks up the accent before you've had time to think about it.

FSI's substitution drills are legendary for a reason. The focus isn't on memorizing grammar rules. It's on assimilating grammar by repeating sentences until it becomes second nature. You repeat variations of a sentence until the pattern lives in your muscle memory. It's boring in the best possible way.

Each one targets a different skill: listening, pattern recognition, recall, production. Here are some of them.

A real dialogue broken into short build-ups, each with audio.

Sound drills targeting the contrasts English speakers find hardest.

Short written explanations of the grammar introduced in the unit.

A sentence with one slot that changes. You produce the full sentence each time.

An English cue paired with a set of German variations to produce.

The unit dialogue rewritten as prose, with an English column to translate from.

A question in German that you answer in German.

New words introduced in context alongside sentence structure practice.

Sentences transformed between forms: singular to plural, present to past.

A core sentence extended by adding new elements one at a time.

Sentences rewritten in a different grammatical form: active to passive, statement to question.

Every new word from the unit, listed with its article.

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The Foreign Service Institute developed this course for US State Department diplomats in the 1960s. The goal: take someone with no German to professional working proficiency, fast. Students spent six hours a day in class, were pushed to speak only German within days of starting, and continued practising outside of class. The audio-lingual method they invented worked then. It works now.

Every single lesson, every drill, every dialogue in DeTawk follows the original 24-unit FSI sequence. We didn't reinvent it. We just made it not look like a government document from 1961.

Unit 1 is live. More units are being added steadily. Here's what's already there.

See the roadmap →Because it works. The FSI course has been producing genuinely fluent German speakers since the 1960s. The audio-lingual method (hear, repeat, drill) builds language intuition rather than vocabulary lists.

Duolingo is optimised for daily active users, not for language acquisition. Streaks, XP, leaderboards. These are engagement mechanics, not learning mechanics. DeTawk is optimised for one thing: you actually speaking German.

The original FSI materials are public domain, produced by the US government and freely available. DeTawk's app, platform, spaced repetition engine, and UX are what you're paying for.

FSI estimates ~750 hours of study to reach B2/C1 proficiency. At 30 minutes a day, that's about four years. At the FSI's classroom pace (full-time immersion), it's 30 weeks. The structure is all there and you just have to follow it.

You can open DeTawk on your phone and get through the content, but it's not fully optimised for mobile yet. A proper mobile experience is on the roadmap.