What format can APIs return?

Question

API

I recently started working with JSON, everything is quite simple and clear. But what other formats can the API return? And how to determine what format it returns? I'm using Postman for requests and so far all the APIs I've tried (xkcd, VK) have returned JSON.

Answer 1

The one that is described in the documentation for the API. And so anyone can, for example xml or plain text in general. Well, the API is not only REST, there is, for example, WinAPI and so on.