Well, no. I mean something I can stick in my actual code to ensure it matches the spec, be it through validation, strongly typed interfaces, unit tests or some other mechanism.

Also, while a nice API document is a godsend (and sadly often missing in practice), a way to generate the consuming side of the API (again via various mechanisms) is also a very useful thing.

Re-reading the page, perhaps I got it wrong and it works the other way around? Voiden uses e.g. OpenAPI files and verifies it's still compliant with them? That would work, although it's a bit of a double effort.. still, useful in many cases.