Mastering RESTful API Design: When to Use Each HTTP Method

What is RESTful API?

In simple terms, a RESTful API is an HTTP‑based, stateless design where every action operates on a resource; the API manages these resources through HTTP verbs.

HTTP Method Semantics

In a RESTful system the client interacts with the server using HTTP semantics. The five most common methods are:

GET: retrieve one or more resources from the server.

POST: create a new resource on the server.

PUT: update an existing resource (client provides the full representation).

DELETE: remove a resource from the server.

HEAD: fetch header information only (no resource body).

Some API designers misuse these verbs, e.g., using GET for actions that should be PUT.

Web Service Resource Types

Clients and servers must agree on media types. Common types that start with application include:

application/json – JSON data format

application/xhtml+xml – XHTML format

application/xml – XML data format

application/atom+xml – Atom XML aggregation format

API Design Principles

URL

Use nouns, avoid verbs.

Deploy APIs under a dedicated domain (e.g., https://api.example.com).

Include version numbers in the URL or HTTP headers.

Path (Endpoint)

Endpoints represent resources; use plural nouns that often match database table names.

Example URLs for a zoo API:

https://api.example.com/v1/zoos

https://api.example.com/v1/animals

https://api.example.com/v1/employees

Media Types

Choose domain‑specific media types and avoid reinventing the wheel.

Typical responses are JSON or XML; some services also provide PHP or Atom formats.

Other Considerations

Extensibility – design so new features can be added later.

Flexibility – support UI requirements.

Portability – run on any operating system.

Developer friendliness – easy to type in a browser.

API Design Process

Source: “RESTful Web APIs” book.