This is the working repository for ‘The API’ book written by Sergey Konstantinov (email, Linkedin profile).

You may find .html, .epub or .pdf version of the book in the docs folder, or read it online.

• In English: html, epub, pdf
• In Russian: html, epub, pdf

Pre-compiled books above comprise clean-copy texts only. Drafts could be found in the src folder. Complete new chapter drafts will be published on:

• my medium blog in English;
• my habr blog in Russian.

I'd appreciate if you share them on reddit, for I personally can't do that: reddit bans me for ‘self-promotion’.

The work is distributed under a Creative Commons Attribution-NonCommercial 4.0 license, meaning in general that you're totally free to use this book in any manner while complying with two rules:

• you're not getting commercial profit from the book;
• you're not forgetting to mention the author properly.

See full license in LICENSE.md file or at Creative Commons Website.

Right now Section I (‘API Design’) is finished. The Section is lacking readable schemes, I'll draw them later.

The book will contain two more sections.

• Section II ‘Backwards Compatibility’ will cover growth issues. Major themes are:
  • major sources of problems leading to backwards compatibility breach;
  • interface decomposing allowing for third-party plugins and switching underlying technologies;
  • structuring public and private parts of your API;
  • versioning policies;
  • common mistakes.
• Section III ‘API as a Product’ will be discussing non-technical issues:
  • what for the APIs exist;
  • monetizing APIs;
  • making sure your understand users' needs and collect proper metrics;
  • common practices, including AA issues and fraud problems;
  • organizing docs portal;
  • open source and community.

I also have more distant plans on adding two more subsections to Section I.

• Section Ia ‘JSON HTTP APIs’:
  • the REST myth;
  • following HTTP spec, including those parts where you should not follow the spec;
  • best practices;
• Section Ib ‘SDK Design’ covering more tricky issues of having proving UI alongside the API (no specific plan right now)

I am translating new chapters into English at the moment they're ready. I'm not a native speaker, so feel free to correct my grammar.

I am accepting inquiries. Feel free to open issues.

I am NOT accepting pull requests introducing any new content, since I'm willing to be the only author. I would gratefully accept typo fixes, though.

Thanks @tholman for https://github.com/tholman/github-corners