My locally running rails app (on localhost:3000) responds to requests in the browser or from curl, but is not responding to requests from the desktop postman client, which immediately gives the generic "Could not get any response". Any idea what could be causing this?
For this you can use NGROK. It provides you a tunnel which can easily be used with postman or anyother such service. Download the library from here and run the tunnel as
./ngrok http 3000
or you can use lvh.me:3000 if your request is from same machine.