MIDI test
Plug in a MIDI keyboard or controller, connect, and watch every key, knob, and wheel show up as you play it.
MIDI test workspace
Privacy: MIDI messages, port names, and the log stay in this browser tab and are cleared when you leave.
How to use
4 short steps.
Connect the controller, then click Connect to MIDI
Plug in and power on the keyboard first. Click Connect to MIDI and allow access when the browser asks.
Play everything
Press keys softly and hard, move knobs, sliders, and both wheels, hit pads, and try sustain and transport buttons.
Watch the keyboard, controls, and log
Keys light up as you play, wheels and knobs update in the controls panel, and every message lands in the log.
Narrow down a problem
Choose one input or channel to isolate a device, clear the log, and play the control you are checking again.
What the result means
Match what you see to one of these.
If a key lights up, the computer received it
If a key lights and the log shows Note on then Note off, the keyboard, cable, and driver all work. Velocity from 1 to 127 shows how hard you played; a Note on with velocity 0 counts as Note off.
If nothing lights, the message never reached the browser
If Connected inputs shows 0, the operating system does not see the device. If it shows 1 or more but nothing lights, check the input and channel filters, then the controller's own settings.
If a knob or wheel moves a bar, it sends control changes
Knobs usually send Control Change with a CC number from 0 to 127. Wheels send pitch bend or CC 1 mod, and key pressure sends aftertouch. The controls panel shows the current value of each.
Troubleshooting
If the test fails, try these in order.
No input appears
Unplug and reconnect the controller, power it on, and confirm it shows in your system's audio or MIDI settings. Click Stop, then Connect to MIDI again.
The device shows but no notes arrive
Close any DAW or app that may hold the port, choose All connected inputs and All channels, and try another USB port or cable. Play a key again.
Only some keys or controls register
Check the controller's octave shift, MIDI channel, and any local-off or zone settings. Reset it to factory defaults, then play the missing keys again.
The browser says Web MIDI is unsupported
Web MIDI works in Chrome, Edge, Opera, and Firefox on Windows, macOS, Linux, and Android. Safari and every iOS browser do not support it. Open this page in one of those browsers and connect again.
What this test can't tell you
Where a browser check stops.
- A message in the log proves this browser received it. Silence does not prove the keyboard is broken; a driver or another app can hold the port.
- Browser timestamps order events but do not measure MIDI, USB, or audio latency.
- The tool only listens through the Web MIDI API. It sends no notes, plays no sound, and requests no SysEx, so it cannot test outputs or firmware.
FAQ
Common questions about this test.
How do I test a MIDI keyboard online?
Plug the keyboard in, click Connect to MIDI, allow access, and play. Each key lights up on the on-screen keyboard and the log shows the note, velocity, and channel.
Why does my MIDI keyboard not show up?
The usual causes are another app holding the port, a missing driver for an older keyboard, a blocked MIDI permission for this site, or a charge-only USB cable. Fix one, then click Connect to MIDI again.
Which browsers support Web MIDI?
Chrome, Edge, Opera, and Firefox on desktop and Android support the Web MIDI API. Safari on a Mac and every browser on iPhone and iPad do not.
Why does Note on with velocity 0 show as Note off?
The MIDI standard lets a device send Note off as a Note on with velocity 0, and many keyboards do. The log shows it as Note off so the key releases correctly.
Can this MIDI test measure latency?
No. The timestamps show when the browser received each message, not how long the keyboard, USB, or audio path took. Latency needs a loopback with an external timing reference.