Design a Web-Scale Search Engine
A worked system design answer for a web-scale search engine: an inverted index sharded by document, and two-phase ranking that avoids scoring billions of pages.
Design YouTube (Video Streaming)
A worked system design answer for YouTube: parallel transcoding into multiple resolutions and adaptive bitrate streaming that reacts to bandwidth mid-playback.
Design a Message Queue (Kafka-like)
A worked system design answer for building a Kafka-like message queue: partitioned append-only logs, consumer groups, and replication for durability.
Design a Ride-Sharing Dispatch System
A worked system design answer for global ride-sharing dispatch: full regional isolation so one region's outage never touches another, plus what stays global.
Design a Payments System (Stripe-like)
A worked system design answer for a Stripe-like payments system: a double-entry ledger that can't silently lose money, and reconciling an ambiguous timeout.
Design a Redis-like Cache
A worked system design answer for a Redis-like distributed cache: approximate LRU eviction, hot-key mitigation, and why this system can skip replication.