How to build an app like Duolingo
The short answer
- An app like Duolingo turns a subject into short daily lessons with quick exercises, progress you can see and a streak that brings people back.
- Recommended stack: an Expo app, Supabase for progress and course content, a small Next.js admin to write lessons, and RevenueCat for subscriptions.
- The hardest part is often not the code but the content: the course is the product, and it needs its own editing tool.
What an app like Duolingo does at its core
Learners pick a course, go through a path of units, and finish lessons of a few minutes each. Each lesson mixes exercise types: choose the right answer, put words in order, match pairs, type a translation, listen and repeat.
The app rewards coming back every day with streaks, points and reminders. A free tier with an optional subscription is the usual model.
MVP features and what comes later
An MVP (minimum viable product) is the smallest version that real users can use and pay for. It tests the idea before you build everything.
In your first version
- One course with a clear path of units and lessons
- Three or four exercise types
- Answer checking that accepts small typos
- Progress per lesson and a daily streak
- One daily reminder at a time the learner picks
- An admin area to write and edit lessons
- Sign up after the first lesson, not before
Later
- Leaderboards and friends
- Speaking exercises with speech recognition
- Lessons that adapt to mistakes
- Hearts, gems and other game mechanics
- Offline lessons
- More courses and languages
- A subscription tier
The recommended stack
This is the blueprint a developer would start from, using the same building blocks as the live builder. It matches the Native Mobile App result of the quiz.
CLIENT
iOS + Android
Expo
CORE
Database + API
Supabase
SUBSCRIPTIONS
RevenueCat
CONTENT
Next.js admin
REMINDERS
Expo Notifications
- Recommended
- Native Mobile App
- Plus
- Web admin for content
- Pieces
- 5 building blocks
Why each layer
- ClientExpo app
Daily learning happens on the phone, in short moments. Native reminders and smooth animations for right and wrong answers matter here, and Expo gives you both on iOS and Android.
- CoreSupabase
Courses, units, lessons and exercises are structured data, stored as rows in Postgres. Learner progress and streaks live next to them, so the app can show exactly where someone is.
- ContentNext.js admin on the same database
Your team writes lessons in a simple web editor instead of asking a developer to change code. This is the piece most first versions forget.
- SubscriptionsRevenueCat
A subscription unlocks extra features in the app, so it must use in-app purchase on iOS (guideline 3.1.1). RevenueCat handles both stores and free trials.
- RemindersExpo Notifications
A daily reminder can be scheduled on the phone itself as a local notification, at the learner's chosen time, without a server sending it.
The hardest parts of an app like Duolingo, and how to solve them
1. The course is the product
Every exercise is content someone has to write, check and fix. Store lessons as data, not in the app code, and give your team an admin editor with a preview. Then a new lesson needs no app update.
Decide early who writes the content and in which format. That decision affects the timeline more than any framework choice.
2. An exercise engine that's fair
Each exercise type is a small component with its own rules. Typing answers is the tricky one: accept small typos, different capitalisation and alternative correct answers, otherwise learners feel cheated.
Start with three or four exercise types and make them feel great, rather than ten that feel rough.
3. Streaks in every time zone
A day ends at the learner's local midnight, not at the server's. Store the time zone with each learner and calculate the streak from it. Travel across time zones is the edge case that breaks naive streak code.
4. Audio and speaking
Listening exercises need audio for every sentence: recorded by people or generated with text to speech. Speaking exercises need speech recognition, which is a step up in complexity and best left for later.
What you can leave out of the MVP
- Leaderboards and friends
- Speech recognition
- Adaptive difficulty: a fixed path works for a first course
- Offline lessons
- More than one course
What it costs
This page gives no price on purpose: the cost depends on your scope and your developer's rate. The App Cost Calculator turns the MVP features above into an hour range, and you add your rate.
Content writing is not in the estimate. Add payments for a subscription and AI features if you plan generated exercises.
Sources for the platform rules and tools mentioned on this page:
Frequently asked questions
What is the most important part of a learning app?
The content. The app is the container, but people stay for good lessons. Plan who writes them and give that person an editing tool from the start.
Do I need AI to build an app like Duolingo?
No. A first version works with lessons your team writes. AI can help later, for example to generate exercise variations or give feedback on answers, but it needs review.
How do daily reminders work?
The app can schedule a local notification on the phone at the time the learner picks. No server is needed for that, and it works even without an internet connection.
How should a learning app make money?
A free tier with an optional subscription is the common model. Subscriptions inside the app go through in-app purchase, which RevenueCat manages for both stores.
Related
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Duolingo is a trademark of its owner. Find My Stack is not affiliated with it; the name only describes the type of app.