Twenty sample system designs, each walked through the way you would handle it in a real 45 to 60 minute interview. No background is assumed. Every building block has a "Why this?" dropdown that explains the choice for this design and why the alternatives lose. Inside it, a "from scratch" dropdown explains the technology itself.
Each example follows the same seven steps:
To practice, read the prompt, then do steps 1 to 4 yourself on paper before you read them. New to a term? The building blocks section at the bottom explains every technology from scratch.
Grouped by theme: web basics, social and messaging, location and booking, media and data pipelines, money and live data. New to system design? Start with an Easy one (use the filter above).
No example matches your filter.
Every technology used above, explained with no background assumed: what it is, how it works, where it shines, where it hurts, and what to pick instead. Each one lists the examples that use it.