Is there actually an API out there that actually qualifies as RESTful, other than the WWW itself? When you really take the time to consider the spirit of RESTfulness, and the designs and constraints of hypermedia in general, I can't really think of anything other than just... websites on the internet. Or some WWW-like that might not be transferred over HTTP nor use HTML but would be functionally the same regardless (and far less popular).

It seems that trying to build a hypermedia API in the spirit of hypermedia precludes someone actually designing an app with any particularity (themes, layouts, pages, certain requests/responses being valid/invalid, etc.), since it must be so general, the only client application that could qualify is the web browser itself - able to render any HTML document without actually knowing about the document semantically. Because having prior semantic knowledge of the API violates REST. Assuming that, are the 'apps' and APIs one would design then just hypermedia documents? Sounds like web 1.0. Not necessarily a bad thing, really, but REST seems too specific to be meaningful outside of websites, either that or I'm not imaginative enough.

I'm not sure what a 'hypermedia API' looks like that isn't just a web page or a functional equivalent thereof. It seems that either the WWW is the REST reference implementation or REST is simply the architecture of the WWW codified.