MIDI Keyboard Tester

Check what a connected MIDI keyboard or controller actually sends. Observe notes, velocity, channels, pedals, wheels, knobs, aftertouch, programs, and raw messages locally in your browser.

Test a MIDI keyboard or controller

See exactly what your keys, pads, pedals, wheels, knobs, and faders send.

Local MIDI input. No recording, upload, SysEx, audio, or output messages.
  1. 1. Connect the deviceUse USB or pair Bluetooth MIDI in your operating system.
  2. 2. Request accessClick the button here—nothing is requested on page load.
  3. 3. Allow MIDIApprove the browser prompt, then play or move a control.
Connect a MIDI keyboard or controller when you are ready.

How to connect and test a MIDI device

  1. 1. Connect and power the controller. Use USB, or pair a Bluetooth MIDI device in your operating system. Class-compliant devices usually need no extra browser setup.
  2. 2. Request MIDI access here. Click Connect MIDI keyboard and approve the browser prompt. The page never requests permission automatically on load.
  3. 3. Play and move controls. Select All inputs or one device, then watch notes, velocity, coverage, controllers, and the bounded live log update.

Understanding notes, velocity, and channels

A Note on contains a MIDI note number from 0 to 127, a velocity, and a channel from 1 to 16. The tester pairs that number with a familiar pitch name such as C4 while keeping the number visible for technical checks. A Note on with velocity zero is treated as Note off, as the MIDI convention requires.

Held means this page observed a Note on for an exact input, channel, and note without a later matching Note off. Disconnecting an input releases its Held display; it does not erase notes already observed during the session.

Testing every key without guessing about hardware health

The A0–C8 piano marks a pitch Seen only after an event arrives and marks it Held while its matching note identity remains active. Pads or transposed notes outside an 88-key piano stay visible in the summary, log, and outside-range chips. An unseen pitch is simply untested here; browser silence alone cannot prove that a key is dead.

Reading the velocity response

Velocity records how strongly a note was triggered, from 1 to 127 in the note-on sample. Minimum, average, maximum, and the newest 32 bars help reveal consistency and range. There is no universal ideal curve: instruments, pad controllers, playing techniques, and configured velocity curves are different.

CC, sustain, pitch bend, aftertouch, and programs

Control Change
Knobs, faders, pedals, and wheels often emit CC values from 0 to 127. Common labels include modulation CC1, volume CC7, pan CC10, expression CC11, and sustain CC64.
Pitch bend and aftertouch
Pitch bend uses a signed 14-bit position around zero. Channel aftertouch applies one pressure value to a channel; polyphonic aftertouch names the individual note.
Programs and timing
Program changes select numbered sounds on receiving gear. Clock and active-sensing events still count in the bounded session, but remain hidden from the rendered log unless you enable timing messages.

Browser permission and device troubleshooting

Web MIDI requires browser support, a secure page, and site permission. If access succeeds but no input appears, reconnect or power-cycle the controller, complete Bluetooth pairing in the operating system, install a manufacturer driver when the hardware requires one, and close another app that may hold exclusive access. Hot-plugged inputs should appear without reloading; Request access again is available when the platform needs a fresh enumeration.

Local input, with no recording or output

The browser supplies low-level input events and bounded port labels directly to this page. They are not uploaded, persisted, or attached to an account. The request explicitly disables SysEx; the tester sends no MIDI output, starts no audio, and loads no instrument. Clear resets only the local observations, while Disconnect removes this page's listeners.

MIDI Keyboard Tester FAQ

Is the MIDI keyboard tester free, and do I need an account?
Yes. The tester is free and does not require an account. In a supported browser, you can explicitly grant this page access to connected MIDI input devices.
Are my MIDI messages or device details uploaded?
No. Port labels and incoming MIDI events stay in your browser. This tool has no recording upload, account storage, analytics event stream, or server action for your MIDI input.
Why does the browser ask for MIDI permission?
Web MIDI access is permission controlled. The page waits for you to click Connect MIDI keyboard, then requests standard input access without System Exclusive access.
Which browsers support the MIDI keyboard tester?
The page checks for Web MIDI support in your current browser and secure context. If it is unavailable, the tester explains that directly instead of showing simulated hardware results.
Why is my MIDI keyboard or controller not detected?
Connect and power on the device, pair Bluetooth MIDI at the operating-system level, unlock it if needed, and close software that may have exclusive access. You can request access again, and connected sessions also watch for hot-plugged inputs.
Why do keys produce no messages?
Confirm that the correct input or All inputs is selected, the device is powered and connected, and the site has MIDI permission. Silence here is not enough to diagnose a key or device as faulty.
What does Note on with velocity 0 mean?
MIDI devices commonly use a Note on message with velocity zero as a compact Note off. The tester normalizes it to Note off and releases that exact port, channel, and note identity.
Can this tester identify a dead key?
No automatic test can prove that from an event it did not receive. The piano marks only Seen and currently Held notes; an unmarked note means it has not been observed in this browser session, not necessarily that it is broken.
Can I test pedals, knobs, wheels, faders, and pads?
Yes. The tester shows all controller numbers, friendly labels for common controls such as sustain CC64, pitch bend, aftertouch, programs, velocity, channel, and bounded raw bytes.
Can I monitor multiple devices and MIDI channels?
Yes. All inputs is the default, or you can select one visible input. Every channel message displays its public channel from 1 through 16, and held notes remain distinct by input, channel, and note.
Does Bluetooth MIDI work?
It can work when your browser and operating system expose a paired Bluetooth MIDI device through Web MIDI. Pair it in the operating system first; this page does not perform Bluetooth pairing.
Does the tester send MIDI output, request SysEx, or play audio?
No. It requests input with System Exclusive disabled, sends no output messages, loads no instrument, and starts no audio. It is an input monitor rather than a synthesizer.

More ways to work with MIDI

  • Free Play — use the computer keyboard or a MIDI input with an audible browser instrument.
  • MIDI Player — open a local file and inspect its piano-roll, score, and tab views.
  • MIDI to JSON Converter — inspect file-based note data or raw Standard MIDI events.
  • Browse songs — find arrangements to play and practice with your controller.