MIDI Monitor

MIDI Monitor is a free macOS utility from Kurt Revis that displays incoming and outgoing MIDI data for troubleshooting devices, apps, and drivers.

Kurt Revis com.snoize.MIDIMonitor

What is MIDI Monitor?

MIDI Monitor is a macOS utility published by Kurt Revis through Snoize for viewing MIDI messages that travel in and out of a Mac. It is commonly used by musicians, audio technicians, and software developers to diagnose MIDI routing problems, inspect controller data, and test MIDI-capable apps or interfaces. The app can show live MIDI events in a document window, filter events by type and channel, and reveal detailed event data including hexadecimal views for deeper inspection. Its documentation also describes options to act as a destination for other programs and to spy on output sent to MIDI destinations, which can help track hard-to-find signal issues. MIDI Monitor integrates with Apple's CoreMIDI environment and may install a helper MIDI driver in the user's MIDI Drivers folder when its spying feature is used. Users typically encounter it as a specialized diagnostic tool rather than a background system component.

Key features

  • Displays live incoming and outgoing MIDI events in real time.
  • Filters messages by category, specific event type, and MIDI channel.
  • Shows detailed event data with hexadecimal and ASCII views.
  • Can save System Exclusive data from supported events to a file.
  • Can act as a MIDI destination for other applications.
  • Can spy on MIDI output sent to destinations for troubleshooting.
  • Can rescan the MIDI system to detect available devices again.

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Safety overview

Status: Safe

This is a legitimate MIDI troubleshooting utility from Snoize/Kurt Revis. It is generally safe to keep if you use MIDI hardware or music software, but saved documents and captured MIDI data may contain session-specific information. The app may also install a user-level MIDI driver to support its output spying feature.

Recommendation: Keep it if you work with MIDI devices, synthesizers, controllers, or audio software and want a reliable inspection tool. Remove it if you do not use MIDI utilities, and also review its related MIDI driver and preference files if you want a complete uninstall.

Common paths

  • /Applications/MIDI Monitor.app
  • ~/Applications/MIDI Monitor.app

Support paths

  • ~/Library/Audio/MIDI Drivers/MIDI Monitor.plugin

Preference paths

  • ~/Library/Preferences/com.snoize.MIDIMonitor.plist

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