Tool

MIDI tester and monitor

Connect a MIDI keyboard, pad controller or knob box, press Start listening, and every message it sends shows up live: notes with their velocity, knobs and faders as CC numbers, the sustain pedal, pitch bend and clock. The keyboard drawing lights each note you play and keeps it green, so a dead key stands out. It runs in Chrome, Edge and Firefox; Safari has no MIDI for web pages.

Test a MIDI device in this order

  1. Connect the device by USB, or pair it over Bluetooth MIDI first.
  2. Press Start listening and allow MIDI when the browser asks.
  3. Play every key once, from the lowest to the highest. Each turns green.
  4. Play one key softly and then hard, and read the velocity range.
  5. Turn every knob, move every fader, press the sustain pedal and the pitch wheel.

Read the result

  • The keyboard drawing. All 88 piano notes, middle C marked C4. A note lights blue while held and stays green once seen.
  • Velocity. How hard each note was struck, from 1 to 127. A key stuck at one value, or one that never goes past a low number, points to a worn sensor.
  • Knobs, faders and pedals. Each control shows as a CC number with its standard name where it has one: CC 64 is the sustain pedal, CC 1 the mod wheel.
  • Pitch bend. From -8192 to 8191, and 0 at rest. A wheel that rests away from 0 drifts like a worn stick.
  • Tempo from MIDI clock. When the device sends clock, the page works out the tempo from it.

The list under the numbers shows every message with its channel. Every key green and every control in the list means the device sends everything it should.

If nothing shows up

Climb this ladder, smallest step first:

  1. Connect first, then press Start. A device plugged in later appears too, but some need the page reloaded.
  2. Allow MIDI. The browser asks once. If you said no, allow it in the browser's site settings.
  3. Use Chrome, Edge or Firefox. Safari does not offer MIDI to web pages.
  4. Check that the Mac sees it. Open Audio MIDI Setup, then Window, Show MIDI Studio. A device missing there is a cable, hub or power problem, not a page one.

What this tester does not do

It listens and never sends, so it cannot test a device's lights, motorized faders or sound. It does not ask for SysEx, the manufacturer messages that can change a device's settings, so those do not show either. Active sensing, the keep-alive message many keyboards send every few hundred milliseconds, is left out of the list on purpose.

Turn the device into shortcuts on a Mac

A MIDI keyboard types nothing on a Mac by itself. InputConfig, the free app I make, turns each key, pad, knob and pedal you just tested into a keyboard shortcut, a click, a phrase or an app launch, in every app. MIDI to keystroke on a Mac has the setup, and the MIDI CC list names every control number. Test it here, then give every pad a job there.

Questions

How do I test my MIDI keyboard online?

Connect it, open this page in Chrome, Edge or Firefox, press Start listening and allow MIDI. Every key you play lights on the drawing, with its note name and velocity in the list.

Why does my MIDI keyboard not show up?

Connect it before you press Start, and allow MIDI when the browser asks. On a Mac, Audio MIDI Setup's MIDI Studio window shows whether macOS sees the device at all.

Does the MIDI tester work in Safari?

No. Safari does not offer MIDI to web pages. On a Mac, open the page in Chrome, Edge or Firefox instead.

Related

Download InputConfig on the Mac App StoreFree. macOS 14 or later. No account, nothing leaves your Mac. Open source on GitHub.