Open beta · Free
The practice-first way to learn system design. Step-by-step lessons, graded quizzes, and an interactive design lab where you build architectures yourself.
01 — Who it's for
Not trivia, not memorized diagrams — the felt sense of why systems behave the way they do.
01
You've read the docs. Now you want to know in your gut why a cache saves a database — or when a queue is the answer.
02
Every concept ends with your hands on a design: place the components, push traffic, watch it break, fix it.
03
Trade-offs, bottlenecks, failure modes. The judgment senior engineers are known for — practiced, not memorized.
02 — Try it
Watch it happen: three components, real traffic, one bottleneck. Then log in and fix it yourself.