Chinese progress
you can actually trust
duiduidui! is the Chinese learning app for people who mean it. It builds a real mathematical model of everything you know, adapts every card to it, and never inflates your progress with points for showing up. When the numbers go up, you're learning.
Most apps teach you to use the app
Points for showing up
Streaks, gems, and XP measure one thing: how often you open the app. You can earn them every day for a year and still freeze when a waiter asks you a question.
Drowning in reviews
Classic flashcard apps let the review pile grow until studying feels like paying off a debt. Falling behind isn't a personal failure. It's a design flaw.
Dictionaries that don't teach
A reference dictionary can tell you what a word means. It can't tell you whether you're ready for that word, or what you should learn next.
Mandarin takes an English speaker roughly 2,200 hours. You deserve tools that take that project as seriously as you do.
A study system that actually models you
Behind every flashcard session, duiduidui! maintains a Bayesian model of your knowledge: every character, word, and phrase you've seen, how well you know it, and how confident the system is in that estimate. A second model tracks your overall skill level, using the same mathematics as standardized testing. A third watches your cognitive load in real time, so you're always challenged and never buried.
Because language is compositional, the models are too. Master a phrase and the system learns something about every character inside it. Learn new characters and it spots the words you're now ready for. There's no placement test and no fixed curriculum: the app calibrates to you within a few dozen reviews and keeps adjusting from there.
How the app updates its belief about your knowledge of a single card, after every review.
We published all of it. Read the mathematics →The whole language, mapped
The duiduidui! dictionary is not a word list. It's a knowledge graph of more than 200,000 entries, purpose-built for learning: 5,100 characters, 51,000 words, 30,000 phrases, and 116,000 sentences, every one linked to the pieces it's made of and the expressions it appears in, and every one scored for difficulty. Look up 好 (hǎo, good) and you can walk outward to 好吃 (hǎochī, delicious), 好看 (hǎokàn, good-looking), and every sentence that uses them.
The entire graph lives on your device. Look up a menu in Chengdu, review flashcards over the Pacific, search by characters, pinyin, or English, and hear natural Mandarin speech for anything you find. No connection required.
You're not learning alone
Every copy of duiduidui! comes with 老虎 (lǎohǔ, "tiger"), an AI tutor that knows the whole dictionary and your entire learning history. Tap 问老虎 (wèn lǎohǔ, "ask the tiger") to ask why a word works the way it does, what to review before a trip, or whether you're ready for HSK 4. It can look things up, create new entries, and organize your phrasebook for you.
Prefer your own assistant? A public MCP server lets Claude, ChatGPT, or Gemini connect to your account with the same tools. And the people in your life come along too: share your real progress with your teacher, and study alongside friends and family.
Working with a Chinese teacher?
Connect with your teacher inside duiduidui! and they see your real progress: every study session, every mastered character, every struggle. Lessons start from where you actually are, and between lessons you're never studying alone.
Serious about learning Chinese?
duiduidui! is now on the App Store. Every new account starts with a 7-day full-access trial: the complete dictionary, the AI tutor, and the adaptive study engine.
Download on the App Store
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