Master Mandarin,
One Card at a Time
duiduidui! is a Chinese language learning app with a huge offline dictionary where every character, word, phrase, and sentence is interconnected — paired with an adaptive study system that models your knowledge and shows you the right card, for the right reason, at the right moment.
Massive Dictionary
Over 160,000 entries — from individual characters to full sentences — spanning every domain from tea culture to biochemistry. Every record includes difficulty scores, compositional breakdowns, and concept tags, giving you a structured path from your first character to real fluency.
Always Offline
The entire dictionary lives on your device. Look up vocabulary on the ground in China, review flashcards on a long flight, or study anywhere without Wi-Fi. No internet connection required. And your study progress syncs to the cloud, so you can pick up right where you left off on any device.
Natural Speech
Listen to natural-sounding Mandarin for any record in the dictionary. Hear individual word pronunciations with clear tones, or practice listening comprehension with full sentences spoken at a natural pace.
Personal Phrasebook
Star any word, phrase, or sentence to add it to your personal phrasebook. Build custom collections of the vocabulary that matters most to you — trip prep, exam review, work jargon — and run focused study sessions on just those items.
Smart Search
Find exactly what you're looking for with search that handles Chinese characters, pinyin (with or without tones), and English — all in a single query. Filter results by tags, difficulty level, or your personal mastery to narrow down the dictionary to exactly what you need.
Adaptive Study
An adaptive flashcard system that builds a mathematical model of your knowledge and selects cards to balance five objectives: discovering new material, reinforcing what you know, building compositional understanding, breaking down complex items, and revisiting stale knowledge. The system monitors your cognitive load so you're always challenged but never overwhelmed.
Real Progress
The scores in duiduidui! aren't XP — they're real measures of your Chinese ability. When the numbers go up, it means you're actually learning, not just engaging with an app. Progress you can trust.
Social Learning
Share your study progress with friends and family who are also learning Chinese, or connect with a teacher who can see exactly where you're advancing and where you're struggling — all backed by real data.