I am building a sort of instagram app with B4x tools. The server part I am using jServer (jetty) with servlet request and response and json as data type. But I am not sure if this is a good solution.
What are you opinions regaring to build such a server app?
Not sure that I understand. Are you asking about the server side? You should use a single server (unless you want to run the solution on multiple machines, however I recommend you to start simple).