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 a Live Leaderboard for a 10M-Player Tournament Premium
Design a real-time leaderboard that updates rankings as scores change during an active tournament with 10 million concurrent players, serves the top-100 rankings in under 10ms, and shows each player their own rank instantly.
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 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.
Build Netflix Adaptive Bitrate Streaming Engine Free
Design the client-side ABR algorithm and server-side infrastructure that switches video quality in real-time based on available bandwidth, minimizing rebuffering while maximizing perceived quality.
Build Netflix's Content Delivery Network Premium
Design a CDN that caches the right content at the right PoP before users request it, handles cache misses without hitting origin, and evicts stale content across 200+ edge locations globally.
Build Netflix's Recommendation Engine Premium
Design a personalization engine that generates a unique homepage for 280 million users, blends collaborative filtering with content-based signals, and updates recommendations within hours of new viewing behavior.
Build a Personalized Typeahead Search Engine Premium
Design a search suggestion system where the same prefix returns different top results per user based on their history, while still surfacing globally trending queries and completing within 50ms end-to-end.
Build a Podcast Transcription and Chapter Detection Pipeline Premium
Design a pipeline that transcribes uploaded audio in near real-time, identifies natural topic boundaries to auto-generate chapter markers, and makes the full transcript searchable within minutes of upload.
Build a Push Notification Routing System Premium
Design a notification dispatch system that routes messages across APNs, FCM, and Web Push, guarantees at-least-once delivery with deduplication, and handles delivery failures with smart retry strategies.