Small source code, real problems. Learn from that very source.

Each mini solution is a small app that solves exactly one problem, drawn from real projects: code that runs on your machine, a design you can rebuild in another language, and a build log that records every decision.

You choose how to learn: build it step by step with the course, get the source to read and extend, or both. The data is made up by 200Lab, not real; the source is a PoC/MVP to learn from and start with, not production.

There is also GonnaCrash, a free game to practice System Design right in your browser.