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 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 a Social Media Hashtag Trending System by Region Premium
Design a system that indexes every post's hashtags, computes trending tags per geographic region updated every minute, and surfaces breakout trends that are gaining velocity even before reaching high absolute volume.
Build a Last-Mile Delivery Tracking System Premium
Design a delivery tracking system that ingests GPS pings from thousands of drivers every few seconds, recalculates ETAs dynamically as conditions change, and streams live location updates to customers without polling.
Build a Live Poll and Real-Time Vote Tally System Premium
Design a polling system that handles 1 million concurrent votes during a live broadcast, shows results updating in real-time for all viewers, and prevents ballot stuffing without requiring user accounts.
Build Meta's Notification Delivery System Premium
Design a notification platform that routes alerts across push, in-app, SMS, and email channels, handles traffic spikes of 10x during viral events, and respects per-user notification preferences in real-time.
Build a Multi-Region Config Management System Premium
Design a configuration management system that propagates changes to 20 global regions in under 500ms, prevents config divergence between regions, and supports instant rollback when a bad config causes elevated error rates.
Build a Real-Time Multiplayer Game State Sync System Premium
Design a game state synchronization system that keeps all players in a match consistent with sub-100ms latency, handles lag compensation so fast-network players don't have an unfair advantage, and recovers gracefully when a player disconnects.