What is an MMON file? An MMON file is a log file created by MIDI Monitor, an app developed by Kurt Revis that records and analyzes Musical Instrument Digital Interface ( MIDI ) data. It stores a log of MIDI messages sent between connected devices or software applications, which may include note on/off events, control changes, pitch bends, and other performance data. MMON files act as a record of MIDI activity, which users can review later for troubleshooting, testing, or analysis.

More Information MIDI Monitor is an app that displays MIDI signals going in and out of a Mac. The primary users of MIDI Monitor are musicians troubleshooting MIDI problems, but programmers may also use it to test MIDI drivers and applications. For example, musicians may use MIDI Monitor in music production or a live performance setup, and programmers may use the app in MIDI software development.