RepreZen API Studio started with the goal of enabling deep interoperability, by unifying data representations across APIs. The core of the product was the API modeling language that became RAPID-ML. API Studio provides the tooling: the RAPID-ML editor, live documentation and diagram views, sandbox testing and code gen framework.
A lot has been written about the Hypermedia Constraint, a.k.a. HATEOAS. I’ll avoid the acronym because… well, because it’s a horrible acronym. I’ll follow Roy Fielding’s example and call it the Hypermedia Constraint.