← Practice
System Design: Core
Work these on the whiteboard, out loud, against the clock. The AI review will not hand you an architecture — it critiques what you drew and asks what an interviewer would ask next, which is the part you cannot practise alone.
4 questions
- Design a URL shortenerThe standard opener. Easy to answer adequately, and the follow-ups are where it is actually decided.mediumWritten#caching#storage#system-design45 min
- Design a distributed rate limiterChoosing the algorithm is half of it. The other half is what happens when the limiter itself fails.hardWritten#distributed-systems#rate-limiting#system-design45 min
- Design a market data distribution systemWhere the usual system-design answers stop working: microseconds matter, and dropping data can be correct.hardWritten#lock-free#low-latency#market-data50 min
- Design notification fan-outPush vs pull, and the celebrity problem that makes the obvious answer fail.mediumWritten#fan-out#queues#system-design40 min