System design interview solutions
Worked answers to 3 classic system design interview questions. Each solution covers requirements, capacity estimates, API and data model, a high-level architecture diagram, and the trade-offs interviewers push on.
Solution library
3 full walkthroughs with diagrams
Haven't tried it yet?
Practice each question stage by stage, or run a timed mock, before reading the answer.
3 solutions
System design primersDesign a URL Shortener
Design a service like TinyURL or Bitly that turns long URLs into short, unique aliases and redirects users back to the original.
Design a Rate Limiter
Design a rate limiter that caps how many requests a client can make in a time window, with token bucket and sliding window strategies.
Design Twitter
Design a social feed that supports posting tweets, following users, and building a low-latency home timeline at scale.
Coming soon: Design Pastebin.
