Does exactly what it says it does.

The app is very simple and allows you to map buttons on your controller to keys/mouse functions on your computer.

Through this app, however, you are unable to assign multiple functions to a single key at different times within a game, as that would be insanely complicated. Thus, the app is fantastic for simple mapping projects and not so great for more complicated tasks. For instance, I used the app to use a PS4 controller while playing Toontown, which is a game with simple controls. It worked great! I could understand though how this would not be ideal for a game like Call of Duty.

OtherFish about Joystick Mapper, v1.1.3