Postman is the real player in this space. They did a great job collecting the low hanging fruit in terms of engaging all types of users in working with APIs. They've been a bit slow since then to build out their full API design and verification functionality, but they are making steady progress, and it seems like UI in 8.0 cleans up a lot of the rough edges they've accumulated over the years.

They also make it simple, if not necessarily easy, to use your collections in other places, either through Newman, API access, or direct export. I know Blazemeter, for example, allows you to build load tests from Postman collections, and it's relatively trivial to have Newman running as part of your CI.

So having worked in this space for the past two decades, and quite recently felt a lot of those same pain points, I'm skeptical of any solution that doesn't either challenge Postman head-on, or build around it.

Without significant financial backing, it will be very difficult to get traction otherwise. That said, I'll certainly take a look at your project, should you share it.