TinyMidiCommander

This app allows to send up to 4 midi commands at the same time to different midi devices (and/or channels) with 1 push of a button.
There are 4 such buttons available in the app's main window.
Each button type can be set to “Push”, “On-Off” or “Step” and each button can have a different name and/or color.
All midi commands (4 per button) and button settings are grouped in a “song” and the main window also allows to switch between songs.
This allows to have a completely different behaviour per song in a gig.
All midi commands are supported but "Program Changes", "Controller Changes" (aka CC) and "Sysex messages" will probably be used mostly.
The buttons can also be triggered from a little status menu in the menubar which can be useful when TinyMidiCommander is not the front application or it's main window is hidden.
And the buttons can be triggered by a received midi command which can make the app a midi translator (receiving a "Note On" can send a "Control Change" , etc ).
All midi commands and button settings for all songs can be saved to  and loaded  from a "show" file.