Build a Distributed Unique ID Generator Free
Design a system that generates globally unique, roughly time-sortable IDs across thousands of nodes with no coordination overhead and zero collisions under any failure scenario.
Build Facebook Live Low-Latency Video Streaming Premium
Design a live video streaming infrastructure that ingests a broadcaster's stream, encodes it into multiple bitrates in real-time, and delivers it to millions of concurrent viewers with under 5 seconds of latency.
Build Facebook News Feed Ranking and Fanout Premium
Design a news feed system that generates a personalized ranked feed for 3 billion users, handles write fanout for posts with millions of followers, and serves the feed in under 500ms.
Build Faceted Search with Live Inventory Filters Premium
Design a search system that supports multi-dimensional filter combinations (brand, price, rating, availability) and reflects live inventory changes in filter counts within seconds of a product going out of stock.
Build a Feature Flag Service Free
Design a feature flag platform that rolls out changes to a targeted percentage of users with zero downtime, supports instant kill switches, and propagates flag changes globally in under 500ms.
Build a Flash Sale System for 500K Concurrent Checkouts Premium
Design an e-commerce checkout system that handles a sudden rush of 500,000 concurrent purchases without overselling a limited inventory, and ensures every confirmed order is fulfilled.
Build a Follow Recommendation Engine Using Graph Traversal Premium
Design a 'Who to Follow' recommendation engine that traverses a social graph of 500 million nodes to find second-degree connections, scores candidates by mutual friend count and activity, and refreshes recommendations daily.
Build a Game Matchmaking System Premium
Design a matchmaking service that balances player skill (ELO rating), network latency, and queue wait time to form fair and low-lag matches, and degrades gracefully by relaxing skill constraints as queue times grow.
Build a Game Replay Storage and Scrubbing System Premium
Design a replay system that records every game event, lets players scrub to any point in a replay with under 1 second seek time, and serves millions of replay requests per day without straining the game servers.
Build a Geospatial Proximity Service Premium
Design a service that answers 'find all X within Y km of this location' in under 10ms at 500 million active entities, supports moving entities that update their location every few seconds.