If you have a server application that doesn’t provide a simple API to access its data, what can you do? Write your own server API?
An easier solution might be to just provide access to the database where the application stores its data, provided you can interpret the data correctly. There are a few packages out there which do just that.
I haven’t tested any of these listed below yet.
Simple, PHP based:
More complicated, runs on Node.JS:
Runs standalone and offers many different APIs: