The concepts behind this design
The same core ideas underpin every system on this site. Master them once, then spot them everywhere.
- The System Design Fundamentals HandbookThe load-bearing ideas behind every distributed system — the CAP theorem and consistency models, concurrency and locking, partitioning and replication, and consensus and coordination — each tied to a real worked design you can study interactively.Learn the fundamentals →
- Partitioning, Sharding & ReplicationHow one dataset becomes many — range vs hash partitioning, consistent hashing and virtual nodes, hot partitions, replication topologies, replication lag, and quorums. Part of System Design Fundamentals.Learn the fundamentals →
- CAP Theorem & Consistency ModelsWhat a distributed system can promise when the network splits — CP vs AP, why "CA" is a myth, PACELC, and the full spectrum from linearizable to eventual consistency. Part of System Design Fundamentals.Learn the fundamentals →
More System Designs
- Design UberBuild a planet-scale ride-hailing system step by step. Learn how to handle real-time location tracking, matching algorithms, scalability, and payments through an interactive diagram that grows with each concept.Read →
- Design a URL ShortenerBuild a URL shortener (think Bitly or TinyURL) step by step. Learn how to mint unique short codes with base62, make the read-heavy redirect path sub-millisecond with caching, shard billions of mappings, and track clicks asynchronously through an interactive diagram that grows with each concept.Read →
- Design WhatsAppBuild a real-time messaging system step by step. See how persistent WebSockets, a session registry, offline inbox queues, the ✓✓ delivery receipts, group fan-out, media on a CDN, and end-to-end encryption fit together — through an animated, live chat-driven diagram that grows with each concept.Read →
- Design TwitterBuild Twitter's news feed step by step. Learn the social graph, why fan-out on write beats read-time merging, how a precomputed timeline cache makes feed reads O(1), how ranking surfaces the best tweets, and how a hybrid model solves the celebrity problem — through an interactive diagram that grows with each concept.Read →
- Design YouTubeBuild a planet-scale video platform step by step. See how raw uploads become an adaptive-bitrate ladder through an async transcoding pipeline, how a CDN serves immutable segments from the edge, how tiered blob storage holds exabytes affordably, and how view counts stay async — through an interactive diagram that grows with each concept.Read →
- Design a Rate LimiterBuild a distributed rate limiter step by step. Learn where to put the check, how to key and tier limits, the token-bucket and sliding-window algorithms, why shared atomic counters in Redis avoid race conditions, and the fail-open vs fail-closed trade-off — through an interactive diagram that grows with each concept.Read →