Duolingo for developers

Stay sharp so you can spot what the AI gets wrong

5-minute drills for real-world patterns. CSS centering, React hooks, Docker builds. No algorithms—just patterns you use daily.

Center a DivEasy
style.css
Preview

Add flexbox properties to center the card

More patterns

Practice patterns for the tools you use

⚛️React
📘TypeScript
🐳Docker
💚Node.js
🐘PostgreSQL
🎨Tailwind
▲Next.js
◈GraphQL
🔴Redis
☁️AWS
⚛️React
📘TypeScript
🐳Docker
💚Node.js
🐘PostgreSQL
🎨Tailwind
▲Next.js
◈GraphQL
🔴Redis
☁️AWS
⚛️React
📘TypeScript
🐳Docker
💚Node.js
🐘PostgreSQL
🎨Tailwind
▲Next.js
◈GraphQL
🔴Redis
☁️AWS
⚛️React
📘TypeScript
🐳Docker
💚Node.js
🐘PostgreSQL
🎨Tailwind
▲Next.js
◈GraphQL
🔴Redis
☁️AWS

Two ways to practice

Build muscle memory, sharpen code review

Write It

Implement patterns from scratch with Monaco editor and live preview.

  • Syntax highlighting
  • Real-time preview
  • Progressive hints
Popular

Spot the Bug

Review AI-generated code and click to flag bugs. Learn why AI makes mistakes.

  • Click-to-flag interface
  • Bug explanations
  • Why AI misses it

Pattern Catalog

Real-world patterns

View all 13 patterns

Write It

6 patterns

Center a Div with Flexbox
easy
Sticky Footer Layout
easy
Truncate Text with Ellipsis
easy
Implement Debounce
medium

Spot the Bug

7 patterns

Missing useEffect Cleanup
medium
Stale Closure in Event Handler
hard
Using Index as Key
easy
Async/Await in forEach
medium

Practice by domain

Focus on what matters to you

Frontend

CSS, React, JavaScript

Backend

Node.js, SQL, APIs

DevOps

Docker, CI/CD, Infra

Ready to build muscle memory?

3 free drills per day. Progress saved locally. No signup required.

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