Build a Distributed Rate Limiter Across 100+ API Gateway Nodes Premium
Design a rate limiter that enforces per-user and per-tenant request limits globally across a horizontally scaled API gateway fleet, with no single coordinator bottleneck and sub-milliseclient enforcement latency.
Build a Distributed Session Store for 50M Active Sessions Premium
Design a session storage system that maintains 50 million active sessions with sliding expiry, serves session data in under 5ms, and handles node failure without logging users out.
Build a Distributed Shopping Cart with Guest Session Merge Premium
Design a shopping cart system that persists items for guest users, merges the guest cart into the authenticated cart on sign-in, handles concurrent modifications, and survives server restarts.
Build a Distributed Tracing System Premium
Design a tracing platform that stitches spans across 50+ microservices into a single request trace, stores billions of spans per day, and lets engineers query any trace by ID in under 1 second.
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 a Distributed Write-Ahead Log Premium
Design a durable WAL that survives single-node crashes, replicates log entries across nodes before acknowledging writes, and supports point-in-time recovery by replaying from any checkpoint.
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 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.