It's bizarre how this specific area of seemingly simple tooling gets churn and VC money.
Maybe I'm out of touch but I still don't know what any of these tools do that you can't do better and more easily with curl.
You can have “collections” of endpoints and their corresponding request schemas organized. So if you’re working with say.. 15 different APIs from different providers all with their own idiosincracies, you get a centralized place to experiment with them