Ace your system design interview

How it works

1. Choose a problem. Pick a real system design interview question from our problem library — URL shorteners, news feeds, rate limiters, chat systems, and more.
2. Design on the canvas. Draw your architecture using a drag-and-drop blueprint canvas or write Mermaid diagram code. Add components, connections, and annotations.
3. Get scored by AI judges. Two AI judges with different philosophies (rigor vs. pragmatism) score your design independently, then debate and reach a consensus verdict with detailed feedback.

Start with a real interview question

• Design a URL Shortener

  Build a service like bit.ly that maps long URLs to short codes at scale.

  Easy hashing caching kv-store

• Design a News Feed

  Architect a social feed with fan-out, ranking, and real-time updates.

  Medium fan-out ranking redis

• Design a Rate Limiter

  Throttle API requests fairly across distributed servers.

  Medium token-bucket distributed redis

• How Uber Finds Nearby Drivers

  Serve 1M RPS geospatial queries with low latency and fresh locations.

  Hard geospatial geohashing quadtree

• Design a Chat System

  Real-time messaging with delivery guarantees and presence.

  Medium websockets queues sharding

• Design a Video Streaming Service

  Deliver adaptive-bitrate video to millions via CDN.

  Hard cdn encoding storage

Learn the concepts first

Study in-depth articles on caching, sharding, message queues, real-time systems, and more — then apply them immediately on the canvas.

Start free. Unlock the judges.

System Design Playground is free to use with full AI feedback included. No credit card required.

• Unlimited practice sessions
• Two AI judges with debate and consensus scoring
• Full written feedback on every submission
• Access to all system design problems
• 27-article learning library