16 core topics · 201 real-time problems · Visual SVG diagrams
Built for Staff & Senior SWE at Google · Meta · Uber · Netflix · Amazon
All concepts, problems, cheat sheets, diagrams — one-time payment.
Complete reference — Foundations, Networking, Security, APIs, Infrastructure, Storage, Caching, Messaging, Consistency, Scalability, Data Pipelines, Distributed Systems, Observability, AI Systems, and more.
Explore Concepts →201 problems across 29 modules — Chat, Video, Payments, Geo/Rides, Queues, Social Feeds, Search, AI/LLM, and more. Each with full architecture + interview cheat sheet.
Browse Problems →Engineers across the globe preparing for system design interviews
Every concept with clear, interactive architecture diagrams
"5 things to say" panels — nail the key points interviewers want
Back-of-envelope math — derive architecture from numbers
Problems link to concepts. Concepts link to problems. Connected.
Slack 10B msg/day, WhatsApp 2B users — real architectures
Deep dives into tradeoffs, failure modes, production decisions