MIDI Keyboard Tester
Plug in a USB or Bluetooth MIDI keyboard, pad controller or synth and press Connect. Every key, knob, fader and pedal shows up instantly: notes light up on an 88-key piano, with velocity, CC values, pitch bend and a full message log.
- Not connected yet
- Not connected yet
Tip: click the keys or use your computer keyboard (A W S E D F T G Y H U J K) to play C4 to C5.
Move a knob, fader, wheel or pedal.
| Time | Type | Ch | Data | Hex |
|---|
How to use the MIDI Keyboard Tester
- Connect your MIDI keyboard or controller by USB or Bluetooth MIDI before or after opening the page.
- Press Connect MIDI devices and allow MIDI access if the browser asks. Your devices appear in the list.
- Play some keys: each note lights up on the piano with its name and velocity. Play softly and hard to check the velocity range.
- Move knobs, faders, wheels and pedals to see their CC numbers and values, pitch bend and aftertouch.
- Tick Play sound to hear the notes, or click the on-screen keys to send notes to a MIDI output.
MIDI messages the tester understands
| Message | Status byte | Data | Sent by |
|---|---|---|---|
| Note on | 0x90–0x9F | Note number 0–127, velocity 1–127 | Pressing a key or pad |
| Note off | 0x80–0x8F (or note on with velocity 0) | Note number, release velocity | Releasing a key |
| Control change (CC) | 0xB0–0xBF | Controller 0–127, value 0–127 | Knobs, faders, mod wheel, pedals, buttons |
| Pitch bend | 0xE0–0xEF | 14-bit value, −8192 to +8191 (0 = centre) | Pitch wheel or touch strip |
| Channel pressure | 0xD0–0xDF | Pressure 0–127 | Pressing harder on held keys (aftertouch) |
| Polyphonic aftertouch | 0xA0–0xAF | Note, pressure | Per-key pressure on MPE and high-end keyboards |
| Program change | 0xC0–0xCF | Program 0–127 (shown as 1–128) | Preset or patch buttons |
| Clock, start, stop | 0xF8, 0xFA, 0xFC | None | Sequencers and arpeggiators (24 clocks per beat) |
The low four bits of the status byte are the MIDI channel: 0x90 is a note on channel 1, 0x9F a note on channel 16. The note number maps to pitch with middle C (C4) = 60 and A4 = 69, and the frequency is f = 440 × 2(n − 69) / 12 Hz. The clock tempo is calculated as 60,000 ÷ (24 × average milliseconds between clock messages).
Checking a keyboard step by step
- Every key: play all keys from bottom to top. Each one should light up once and go dark on release. Notes held should return to 0.
- Velocity: play one key softly, then hard. The minimum and maximum next to the meter show your playable range.
- Octave and transpose buttons: press a key, change octave on the keyboard and press it again. The note number should move by 12.
- Wheels and pedals: the pitch wheel should spring back to 0, the mod wheel should send CC1 from 0 to 127, and the sustain pedal should show Down and Up. A pedal that works backwards needs its polarity switch flipped or the keyboard restarted with the pedal up.
- Knobs and faders: each control should send its own CC number across the whole range 0 to 127 without jumps.
Common CC numbers
| CC | Usual function | CC | Usual function |
|---|---|---|---|
| 1 | Modulation wheel | 64 | Sustain (damper) pedal, 64+ = down |
| 7 | Channel volume | 66 | Sostenuto pedal |
| 10 | Pan | 67 | Soft pedal |
| 11 | Expression pedal | 74 | Filter cutoff / brightness |
| 0 / 32 | Bank select MSB / LSB | 123 | All notes off |
Frequently asked questions
Which browsers support the MIDI keyboard tester?
The test uses the Web MIDI API, which works in Chrome, Edge, Opera and other Chromium browsers on Windows, macOS, Linux, Android and ChromeOS, and in Firefox 108 and newer. Safari on Mac, iPhone and iPad does not support Web MIDI, so use another browser there.
Why does my MIDI keyboard not show up?
Check the cable and that the keyboard is powered on and set to USB MIDI mode, then press Connect MIDI devices again. Close other apps that may hold the device exclusively, such as some DAWs on Windows. Some keyboards with only 5-pin DIN MIDI need a USB MIDI interface. Bluetooth MIDI devices must be paired in the operating system first.
How do I test velocity on my keyboard?
Play the same key from very softly to very hard and watch the velocity number and meter. Velocity ranges from 1 to 127. A healthy keyboard should reach low values around 10 to 30 and high values above 110; if it always sends the same value, velocity may be switched off or set to a fixed curve in the keyboard settings.
What are CC numbers?
Control Change (CC) messages carry the position of knobs, faders, wheels and pedals as a value from 0 to 127. Common ones are CC1 modulation wheel, CC7 volume, CC10 pan, CC11 expression and CC64 sustain pedal, where values of 64 and above mean the pedal is down. The tester shows each CC number your controller sends.
How do I find a stuck or dead key?
Play each key in turn and watch the piano. A dead key never lights up; a key that stays lit after you release it means the note off message was lost, and Notes held stays above zero. A key that triggers twice or with very uneven velocity may have a dirty or worn contact.
Is the MIDI data sent anywhere?
No. MIDI messages are read and displayed in your browser only. Nothing is uploaded or stored.