MIDI Router 4+

MIDI Router is a utility for controlling and monitoring MIDI traffic on your Mac. MIDI data can be transformed between inputs and outputs for practical tasks like reassigning devices to specific MIDI channels, altering note velocities, filtering messages, etc. You can also write scripts which not only alter data but also create new MIDI events, to do anything from converting CC to sysex, to building your own interactive sequencers, auto-accompaniment engines, and even games. A monitor window lets you check up on the data being sent between inputs and outputs, (especially useful in troubleshooting situations) as well as custom messages from your scripts. An optional menu item is added to the macOS system menubar, so you can leave the app running in the background and check in easily no matter what else you might be doing.