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 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 a DRM Token Vending System for Premium Video Premium
Design a digital rights management system that issues short-lived playback licenses to authenticated subscribers, prevents license sharing across accounts, and revokes access instantly when a subscription lapses.
Build an Event Sourcing and CQRS Audit Trail Premium
Design an event-sourced system where every state change is stored as an immutable event, supports replaying 3 years of history to reconstruct any past state, and separates read and write models for query performance.
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 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 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.