Author here. I kept bouncing between paywalled courses and link dumps while prepping for system design interviews, and wanted one place where each design is worked end to end and you can click into the architecture instead of squinting at a PNG.

Up front: most of the writing is LLM-generated. I picked the topics, set the structure and reviewed the pages, but the prose isn't hand-written.

The architecture diagrams are real React Flow canvases rather than images — they pan, zoom and go fullscreen, and every node is clickable, showing what it's for, its trade-off, and a link to the concept module explaining it. Node colour is by kind across every diagram, so the same colour always means the same thing.

The numbers are interview-grade rather than measured, so treat them as a starting point. Corrections are the most useful thing anyone can send — that's the main reason it's open source.