Build a Hot-Cold Tiered Storage System Premium
Design an automated data tiering system that keeps frequently accessed data on fast NVMe SSDs, migrates aging data to object storage, and retrieves cold data transparently on access without application changes.
Build Instagram Stories Expiry and Archival Pipeline Free
Design a system that automatically expires 500 million Stories after 24 hours, moves them to cold archival storage, and lets users retrieve archived Stories on demand without impacting live traffic.
Build an Inverted Index for Full-Text Search at 10B Documents Premium
Design a full-text search engine that builds and maintains an inverted index over 10 billion documents, returns results with relevance ranking in under 100ms, and updates the index in near real-time as documents are added.
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 a Multi-Tenant Database System Premium
Design a database architecture that isolates tenant data, prevents noisy-neighbor query interference, and allows individual tenants to be migrated, backed up, or throttled independently - all on shared infrastructure.
Build a Payment Processing System with Idempotency Guarantees Premium
Design a payment system that safely retries failed transactions without double-charging users, handles partial failures across payment provider integrations, and maintains a consistent ledger under concurrent requests.
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 Semantic Search Engine with Hybrid Ranking Premium
Design a search engine that combines keyword-based BM25 scoring with dense vector similarity to handle queries where exact keyword matches are absent but semantic intent is clear.
Build a Social Graph Service at 500M Users Free
Design a graph service that answers 'does user A follow user B?' in under 1ms, supports mutual friend queries, and stays consistent as billions of follow/unfollow events happen every day.
Build a Time-Series Metrics Store Premium
Design a metrics storage engine that compresses billions of data points efficiently, supports fast range queries for dashboard rendering, and retains high-resolution data for 15 days before downsampling.