Blueprint 101 — system design, drawn by hand

System design prep is scattered across blog posts, videos and a few famous repos. Blueprint 101 pulls it into one structured path: 96 in-depth notes, 126 hand-drawn diagrams, 306 interview questions and 10 interactive labs — from fundamentals all the way to consensus.

• Notes from DNS and caching to sharding, sagas and consensus — each ends with interview questions and answers
• Hand-drawn (Excalidraw-style) diagrams, every one with an editable .excalidraw source
• Case studies: URL shortener, Twitter, WhatsApp, YouTube, Uber, payments, web crawler and more
• Runnable builds in Python: LRU cache, rate limiters, consistent hash ring, Bloom filter, LSM key-value store, circuit breaker

The notes compile into a static reader with search, study plans, spaced-repetition flashcards generated from every Q&A, a diagram gallery and labs (capacity estimator, load balancer, hash ring, rate limiter, cache eviction, quorum and more). Progress lives in the browser — no account, no server. Small Python tools render the diagrams, sync the builds into the notes and lint every note.

Writing every note, drawing every diagram and coding every build by hand is the best way I know to actually understand a system — the repo is as much my study log as it is a resource.