REST API Design

If you have already built a REST API but still find yourself second-guessing naming conventions, arguing about status codes, or discovering mid-project that your versioning strategy is a dead end, this book is for you. You do not need an introduction to what an API is. You need a clear, opinionated reference for the design decisions that come up again and again, with the reasoning behind each one so you can apply it confidently in any context.

This is not a tutorial. It is the book you hand to a backend developer who is building or maintaining a production API and needs to stop reinventing the same wheels.

What you will find inside:

• A precise, no-filler guide to URL structure, resource naming, and HTTP methods, including the rules most developers only discover after they have already broken them
• The right way to handle errors consistently across every endpoint, including when to use RFC 7807 Problem Details and what never to expose in an error response
• Versioning strategies with honest trade-offs and a clear recommendation, plus exactly what constitutes a breaking change
• Authentication patterns covering API keys, Bearer tokens, OAuth 2.0 flows, scopes, and the critical difference between 401 and 403
• Pagination, filtering, and sorting done right, including cursor-based pagination and when offset pagination will quietly break on you
• Idempotency keys explained from first principles, with a complete implementation pattern for any POST that creates a resource or triggers a side effect
• Webhooks from payload design to HMAC-SHA256 signature verification, with signing code in Python and Node.js
• Rate limiting, caching, CORS, ETags, and the response headers that infrastructure and monitoring systems depend on
• A full chapter on the thirteen most damaging API design mistakes, each with a description of the problem and the correct fix
• A Quick Reference covering the HTTP method decision guide, status codes by use case, standard headers, a reusable error response template, and an idempotency implementation checklist

Every recommendation in this book comes with a reason. When there is a genuine trade-off, both sides are presented honestly before a recommendation is made. When one approach is clearly better, it is stated directly. The goal is not to give you a style guide to memorise but to give you the judgment to make good design decisions independently, on any API, in any team.

If you want your API to be the kind that developers praise in code reviews rather than quietly work around, this is where to start.