The USB MIDI Monitor is a free Android app developed by eXtream Software Development that allows you to view all incoming MIDI events from your USB MIDI interface. This app is designed for musicians who want to monitor the MIDI data coming from their USB MIDI interface to ensure that what they are playing is what they are hearing.

With the USB MIDI Monitor, you can easily view all incoming MIDI events on your Android device. The events are timestamped, and the event type, MIDI channel, and values are displayed in a scrollable table. If the control change is a known type like volume or panning, extra information is displayed.

The app is compatible with Android 3.2 or higher and requires a tablet or phone with USB host support. You will also need a USB MIDI interface that works without drivers on Windows or OSX, and if your device has a micro-USB connector, you will need a micro-USB to USB OTG cable (around 7 to 10 euro). The app does not require rooting or special drivers.