I'm doing some investigation for the server side component of my, so far, clientside only project.
The server library #ktor is pretty nice and simple so far, all non-blocking/coroutine based which is neat. And a very ergonomic API.
Also, no need for Post Man for testing! The IDE understands the library, picks out the end points i've defined, and then you can execute requests against them and see the response all right in the IDE, pretty slick developer experience!