REST Fundamentals
Practice this topic in a realistic system design interview
Building an API that works is relatively straightforward. You create a few endpoints, accept some JSON, return a response, and the client can start using it.
The real challenge is designing an API that remains easy to use and maintain as it grows. Once other teams, mobile apps, or external customers depend on your API, even small changes can cause problems:
- Rename a field, and an existing client might break.
- Use different conventions across endpoints, and developers have to learn how each one works separately.
- Handle errors inconsistently, and clients end up needing special logic for every endpoint.
A well-designed REST API avoids many of these problems by following clear, consistent conventions. Ideally, once a developer understands one part of your API, they should be able to predict how the rest of it works.
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In this chapter, we will look at how to design a clean REST API, from naming resources and choosing HTTP methods to status codes, pagination, versioning, and caching. We'll use a simple e-commerce system with customers, products, and orders as our running example.
Let's start with the foundation of REST APIs: resources.