System Design Simulator

Learn by doing. Predict what will happen, watch it break in slow motion, turn on the fix, and compare the numbers before and after.

Courses

Course 1System design, hands onEvery building block of a large system, from app servers to observability, then full system designs.20 modules · 219 lessonsStart the course →Course 2 · newAI engineering, hands onBuild on large language models: prompts, RAG, agents, evals, safety and production.1 of 18 modules ready · 11 lessonsStart the course →

Build it yourself

Ten missions in the system builder: design the architecture yourself, run launch day, and earn up to three stars.

  1. Lesson 1Why does it get slow before it breaks?Not started
  2. Lesson 2Why do we need a load balancer?Not started
  3. Lesson 3Why stateless servers?Not started
  4. Lesson 4Why do we need a cache?Not started
  5. Lesson 5Why indexes?Not started
  6. Lesson 6Why read replicas?Not started
  7. Lesson 7How big should the cache be?Not started
  8. Lesson 8When replicas don't helpNot started
  9. Lesson 9Bigger box or more boxes?Not started
  10. Lesson 10Why did my post disappear?Not started
Sandbox: build your own system →

No lesson, no mission: every box, any traffic.