I am in the process of creating an app (cross-platform with Ionic framework) and during my research about app with this framework I found the one created for HabitRPG and it is using an API to retrieve data, it totally suits my app as well, but I don't know where to start to create an API nor what to use.
I allready did some quick test with Spring, NodeJS and Symfony (with FOS) but I'm looking for something really easy to use and to setup but still to have a lot of flexibility (like manage security, users, and data visibility).
Is there a specific technology easy enough to start with ?