How to check MIDI data during a live keyboard setup

Your keyboard lights up, but you are not sure whether it is sending the right MIDI data to your computer. Or a note, knob, sustain pedal or controller works in one part of your setup but not another.

Check the keyboard directly before changing your live software setup. TooLab's MIDI Test can show incoming key, velocity, knob, pedal and message activity in your browser. It checks MIDI input, not the sound coming from the keyboard.

Check the keyboard's MIDI data

1. Connect the keyboard to the computer by USB, or connect its MIDI output through a MIDI interface. Turn the keyboard on, then open the MIDI Test in a desktop browser. The test does not work in Safari, so use a different browser if you are on a Mac.
2. If your browser asks for permission to access MIDI devices, allow it. If the test offers a way to choose an input, select the keyboard or MIDI interface you are checking.
3. Press and release one key at a time. Watch for the key and its messages to appear, and check that the key stops registering when you let go.
4. Play the same key softly and firmly, then try the controls you use on stage, such as knobs, sliders and pedals. Check whether their messages change as you move or press them.

Keep other MIDI programs closed for the first check so you can clearly see what reaches the browser. If you use a multi-port interface, test one keyboard output at a time.

What the result means

Keys and messages appear when you play

The computer and browser are receiving MIDI from the selected input. If your live software still does not respond, check its input device, track routing, channel and instrument settings. A MIDI message does not prove that the software is set to play a sound.

A key appears, but the release seems missing

A played note normally sends a start message and a release message. Some keyboards send Note Off; others use Note On with velocity 0 to signal release. If neither appears when you let go, the keyboard may be sending incomplete data, or a setting or controller is interfering.

Notes appear, but velocity barely changes

Velocity is how hard a key press is reported, usually on a scale from 1 to 127. If soft and firm presses show similar values, check the keyboard's velocity curve or whether the patch has a fixed-velocity setting. A browser test can show the value sent, but cannot tell you how a particular instrument will sound at that value.

Keys work, but a pedal or knob does not

Many pedals and knobs send Control Change messages, often shortened to CC. If key messages appear but a control does not, check that the control is assigned to transmit MIDI and that the pedal is connected to the correct socket. Some controls send data only after you move them.

Nothing appears

The browser is not receiving input from the selected device. That does not yet prove the keyboard is broken. Check permission, the connection and the input choice before testing again.

How to fix missing or incorrect data

1. Check the browser permission. If you dismissed the MIDI access prompt, reload the test and look for a new permission request. You can also open the site permissions from the icon beside the browser address bar and check whether MIDI access is blocked.
2. Reconnect the keyboard. Unplug and reconnect its USB cable, or disconnect and reconnect the MIDI interface. Try another USB port and avoid a hub while troubleshooting. For a Bluetooth MIDI device, check that it is paired and connected in Settings › Bluetooth & devices on Windows 11 or System Settings › Bluetooth on macOS.
3. Check the keyboard's MIDI output. Confirm that it is set to transmit over the connection you are using. If the keyboard has multiple MIDI ports or zones, verify that the playing part is assigned to the port and channel your setup expects.
4. Test one control at a time. Move a knob through its full range, press and release the pedal, then try another control. A pedal's polarity or mode can make its action seem reversed, while an unassigned control may send no data at all.
5. Close other MIDI software temporarily. Quit your DAW, virtual instruments and MIDI utilities, then reload the test. This removes other setup variables. After the browser test, reopen your live software and confirm that it is listening to the same device.
6. Restart the browser and computer. A fresh connection can clear a stuck device session. Reconnect the keyboard before opening the browser test again.

When the keyboard or connection may be faulty

Try the keyboard with another cable, port or computer, changing only one thing at a time. If a particular key or control consistently sends no data across different setups, while other keys or controls work, the problem may be in the keyboard or its connector. If all controls fail through one interface but work through USB or another interface, inspect or replace the interface or cable.

If the keyboard is under warranty, contact the manufacturer before opening it. For a damaged socket, intermittent keybed or failed pedal input, arrange a repair or use a replacement part rather than relying on a live workaround.

Separate MIDI input from sound

MIDI carries performance instructions, such as which note to play and how hard to press. It is not audio. A keyboard can send notes to the browser while producing no sound, and it can make sound locally without sending MIDI to the computer. For a live setup, check MIDI data first, then check the receiving software's input selection, track monitoring and sound output.

If a device sends extra or unexpected messages, see how to test MIDI message filtering on a web page for another way to investigate what is reaching the browser.