In my opinion, it's great for web app backends as well. The net/http library suffices.
Just that you might need a library for routing like https://github.com/julienschmidt/httprouter
Just that you might need a library for routing like https://github.com/julienschmidt/httprouter
Also Go is one of the few (if not only?) languages with HTTP/2 built in to the standard library. Not to mention the gRPC over TLS that comes stock as well.