← System Design learning pathSystem Design · Module 9 of 10
Classic design problems
Practise common system design questions.
📖 Key ideas
- URL shortener: ID generation, redirect, caching, analytics.
- Chat app: WebSockets, message storage, delivery status, presence.
- News feed: fan-out on write vs read, ranking, caching.
- Rate limiter: token bucket or sliding window.
- File storage: object storage, metadata DB, CDN.
💡 Real-life example: Classic problems are practice matches: the same skills apply in the final (real projects).
URL shortenerMaps short codes to long URLs
Fan-outDelivering one post to many feeds
Token bucketRate limiting algorithm
PresenceOnline/offline status