Isn't testing at the UI level more than enough? Why should you be testing your application's APIs, as well? What is REST API testing anyway? What more would you gain from testing your software application at the API level, too? And, most of all: how to do API testing? Especially since API has no GUI... And what “deeper” layer would you be actually testing? What test types and test cases to use/define? “Tormented” by all these legitimate questions here? You're entitled to be, since just the idea of getting tangled up in integration complexities, in the “spiderweb” of connections between...