AudioSwift

AudioSwift transforms your trackpad into a set of MIDI tools, like sliders, triggers, XY pads, mixing controllers, and MPE.

With support for MacBooks and Magic Trackpads, the app runs in the top menu bar waiting to be called. You must tap the trackpad with a four-finger tap gesture to activate. Consequently, a console window appears showing the current controller mode. You can then start sending MIDI with simple touch gestures and when you finish, you press the Esc key to turn AudioSwift off.