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 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.
Build Gmail's Spam Detection Pipeline Premium
Design a spam classification system that processes 300 billion emails per day, classifies each one in under 100ms before delivery, and continuously retrains models as spammers adapt their tactics.
Build Google Docs Real-Time Collaborative Editing Premium
Design a collaborative document editor where multiple users can type simultaneously, see each other's cursors in real-time, and never lose edits even when two users modify the same paragraph at the same time.
Build Google Drive's File Sync Engine Premium
Design a file synchronization system that detects changes on any device, propagates them to all other devices within seconds, handles concurrent edits, and resolves conflicts without data loss.
Build Google Maps ETA Prediction Under Live Traffic Free
Design a route ETA system that incorporates real-time traffic signals from millions of moving devices, recalculates ETAs en route as conditions change, and serves predictions with under 200ms latency.
Build Google Photos Duplicate Detection Pipeline Premium
Design a pipeline that detects near-duplicate photos across 28 billion uploads per day using perceptual similarity rather than byte-level matching, and does so without storing a full copy of every image.