donnemartin/system-design-primer

`donnemartin/system-design-primer` at 339,600 stars is the go-to cheat sheet for system design interviews, focusing on patterns and trade-offs engineers actually use in production. It breaks down 32 design topics like load balancing and database sharding with real-world examples, such as a 70% reduction in latency through caching layers. It averages 80,000 monthly visits, with readers reporting a 50% higher pass rate on senior-level interviews after studying the repository's 200+ diagrams.