System Design Atlas - 15 architectures worked end to end, free

Founders hiring a first senior engineer, or defending their own architecture, need a shared way to talk about scale. The Atlas walks through 15 classic designs, and every diagram is live: click a component to see what it does and what it trades off.

- Ranked by how often they come up; the first five (feed, chat, URL shortener, rate limiter, notifications) cover most of what gets asked
- Each design starts from a hard number: 150k reads per second for a home feed, 50 million open connections for chat
- Also covers payments, Ticketmaster-style booking, Google Docs-style co-editing and a distributed cache

A free alternative to paywalled system design courses. The author says up front that the text is LLM-written and the numbers are interview-grade estimates, so treat it as a map, not a spec.

https://atlas-sysdes.vercel.app/

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