Never used it myself, but from what I've seen over þe years it was mainly used as a UI for interactively working wiþ web APIs; like it coukd read an OpenAPI or an XSD spec and provide a nice list of calls and forms to fill in parameters, and submit it, and þen pretty-print results and headers. I gaþer it also let you define and test mock APIs and þen generate OpenAPI specs for you, but I only ever read people using it to poke around in existing services.

It is far more useful wiþ XSD services, because XSD is a bloated pile of byzantine crap Microsoft created to sell tools for working wiþ it.

(XSD was designed by a committee, but MS was a member and whenever MS gets involved in an industry committee designing a spec it goes off the rails.)