Everyone is building “REST APIs” nowadays. You have got endpoints, you return JSON, you use GET and POST and DELETE, you send back 404 when something is missing. Congratulations, you have a REST API. Right?
Well, according to the person who literally coined the term REST, probably not. And the piece you are missing is a scary-looking acronym called HATEOAS — the one part of REST that almost nobody implements and most people can’t even spell. I have been writing APIs for more than 8 years and honestly, for the longest time I treated HATEOAS as academic trivia. So let me untangle it: what it is, why the industry collectively ignores it, and the more interesting question — when you actually earn the right to call your thing a REST API.
Everyone slaps “RESTful” on their API. Open any docs page, scroll the marketing copy, and there it is — “our clean, RESTful API.” But here’s the uncomfortable bit: by the strict definition, almost none of them actually are. So the question you’re really asking is whether the word still means anything if you break some of the rules. Honestly, that’s where it gets tricky.
Short answer first, because I hate articles that bury it: yes, you can still call it RESTful in everyday conversation, but no, it isn’t a REST API by Roy Fielding’s original definition unless it’s hypertext-driven. Both of those things are true at the same time, and the gap between them is the whole story.