handbook.academy · an open library
Engineering handbooks,taught the way you'd want to learn.
Single voice. Plain prose. Living docs. Free, open-source, no sign-up — 279 chapters across 2 books, with 2 more on the way.
- Live
The HLD Handbook
System design, done right
- Chapters
- 159
- Words
- ~580K
- Beta
The DSA Handbook
Algorithms, taught right
- Chapters
- 120
- Words
- ~278K
- 2026 · planning
The LLD Handbook
Object-oriented design, patterns, refactoring, and testing — for engineers who already write code professionally.
In writing - 2026 · planning
The AI Engineering Handbook
LLM applications, prompts, RAG, evals, agents, and inference cost — for engineers shipping AI features into production.
In writing
What makes it different.
Three rules the whole library follows. They’re also why everything stays free.
Free, forever.
CC BY-SA 4.0 content. MIT code. No paywall, no ads, no email gate, no “sign in to continue.”
One author, one voice.
No CMS, no committee, no SEO copy. Every chapter reads like the same person taught it — because they did.
Living docs.
Updated when the truth changes. Mistakes get fixed. Every page carries a
date_updatedyou can audit.
Pick a book. Start reading.
Both live books open immediately — no account, no setup.
Watching the LLD or AI Engineering handbooks? Star the repo and you’ll know when each one ships.