Bluetooth Terminal allows you to chat simply with a bluetooth device via a terminal. It is very usefull for example when you're working with Arduino or other electronic stuff.

I personally already tried to connect to the HC-06 module and it worked perfectly!
If you have trouble to connect to a device, try to unpair to this device and then pair with it. It may fix the problem.

Github: https://github.com/omaflak/Bluetooth-Android
Sample for the HC-06: https://en.causeyourestuck.io/2015/12/14/communication-between-android-and-hc-06-module/