System design interview solutions
Worked answers to 4 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
4 full walkthroughs with diagrams
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Practice each question stage by stage, or run a timed mock, before reading the answer.
4 solutions
System design primersDesign a URL ShortenerVideo
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 LimiterVideo
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 PastebinVideo
Design a service that lets users store and share text snippets with shareable links, expiration, and read-heavy access patterns.
Design TwitterVideo
Design a social feed that supports posting tweets, following users, and building a low-latency home timeline at scale.