This page needs a secure browser context with Web MIDI support and an allowed permissions policy. Keep security protections enabled. A refusal stops this attempt; no permission retry runs in the background. Unsupported and denied do not mean your keyboard is broken.
MIDI Input Test: Check Notes, Velocity and Release
Connect a MIDI keyboard or controller and check whether this browser receives notes, releases and velocity from one input. This is an input monitor, not a synthesizer or tuning tool.
Also known as: midi test. Free, online, and no download required.
midi, permission requiredNothing uploaded
Start MIDI input test requests browser access only after your click. Then choose one input port; no sound or MIDI output is used.
01
What the MIDI Input Test: Check Notes, Velocity and Release checks
| Check | How it is measured | Fails when |
|---|---|---|
| Input access | Available connected MIDI input ports after one deliberate browser access request, with system-exclusive and software access disabled. | Unsupported, permission denied and no inputs are different states. None establishes that a physical instrument is faulty. |
| Notes and releases | Channel 1 to 16, note number 0 to 127 and velocity 0 to 127 from complete Note On and Note Off messages. Note On with zero velocity is a release. | No event means no matching input reached this listener. Missing or invalid bytes are ignored rather than filled with zero. |
| Control changes | The raw controller number and value from a Control Change message, shown separately from note presses. | A pedal or knob may use another message type, another port or another device configuration. A CC does not count as a tested physical key. |
How to run the MIDI Input Test: Check Notes, Velocity and Release
- Connect your device using its normal MIDI connection, then press Start MIDI input test. Confirm the browser permission yourself if a prompt appears; a denied request is not repeated automatically.
- Choose one MIDI input port. Press and release one key, then compare its note number, channel and velocity. Move a control separately to check a Control Change message.
- Repeat your own physical-key checklist and mark it complete only if you actually checked those controls. Stop or Finish removes listeners and requests port closure; Reset also discards the log.
If something failed
Check the device's ordinary connection and input configuration. Choose the port explicitly and try one intended key in the foreground. An input listed by the browser is not proof that an event will arrive. This tool does not send test data back to a device.
A change in connected input devices removes the previous listener and clears the active-note set. Re-select a connected port for a new sample. Ordinary open and close notifications are not a physical disconnect. A failed closure is reported separately; the message handler is still removed.
02
How to read the result
Read one press and its release
Compare the event type and channel before deciding whether a key stayed down. Active notes are displayed as channel:note pairs, because the same note number on two channels is not one identical input. The event table is a rolling sample, not a saved record of all keys you touched.
| Input example | Displayed meaning |
|---|---|
| 0x90, 60, 100 | Channel 1, note 60, velocity 100: Note On. |
| 0x90, 60, 0 | Channel 1, note 60: Note Off. Zero velocity releases this active note. |
| 0x80, 60, 64 | Channel 1, note 60: Note Off with release velocity 64. |
| 0x9F, 127, 127 | Channel 16, note 127, velocity 127: Note On. |
| 0xB0, 64, 127 | Channel 1, controller 64, value 127: Control Change, not a note press. |
Your checklist is separate from events received
Events received means at least one supported message arrived. It does not mean the page knows which keys, pads, knobs or pedals your particular device contains. Make a short physical list first, check each item deliberately, and use the checkbox only to record your own observation.
- Test one key at a time before trying several together, so you can match presses and releases.
- Compare velocity values only as numbers returned by this device; this tool does not calibrate physical force.
- For computer typing keys use the separate keyboard test. MIDI note input and operating-system typing events are different paths.
Session storage and cleanup
The newest 100 valid events stay in this tab's memory. The oldest event is dropped when the next arrives. MIDI device names are shown only in the local selector; neither names nor bytes are uploaded, placed in analytics, or persisted to browser storage.
- Changing ports clears the previous log and active notes, removes the old handler and closes the opened input before opening the next.
- Stop and Finish leave the bounded log available to read, but disconnect it from incoming messages. Reset stops the session and clears the log.
- Leaving the page or hiding the tab stops listening. Returning does not restart access. Any access or open promise that returns late cannot restore a stopped session.
Measurement limits
This test observes messages delivered to one browser input. It cannot certify every key, identify electrical wear, measure USB hardware latency, or confirm how a music application handles the same device. Note numbers are used instead of octave names because octave naming conventions differ.
- Only complete three-byte Note On, Note Off and Control Change messages are decoded; other types are counted as unsupported, not treated as failed keys.
- No system-exclusive access, MIDI outputs, sound generation, tuning or pitch detection is requested.
- API behavior follows MDN's Navigator.requestMIDIAccess() and MIDIMessageEvent.data documentation, reviewed October 14, 2026. The three-byte status meanings follow the MIDI Association message reference. These are protocol references, not a measurement of your physical instrument. Return to all tools for other hardware tasks.
03
MIDI Input Test: Check Notes, Velocity and Release questions
Does the MIDI input test make a sound?
No. It listens to the selected input and displays note or control messages only. There is no synthesizer and no device output. A silent result is expected; it says nothing about the instrument's speakers or a music application's audio configuration.
Why does zero velocity appear as Note Off?
MIDI Note On with velocity zero represents release. The monitor removes that channel:note pair from active notes, just as it does for a Note Off message. It preserves the returned zero rather than inventing another release value.
Why are there note numbers instead of C4 or C5?
Different devices and applications label octaves differently. Note number 60 is an unambiguous returned number; an octave label could imply a convention this page cannot establish. Compare matching note numbers and channels when checking a press against its release.
Can received MIDI messages certify my whole keyboard?
A received message confirms this sample, not the entire instrument. Check your intended physical controls yourself and record that checklist separately. A short clean sample cannot exclude an intermittent fault, and a CC message cannot fill a missing key-press check.
What should I do when my MIDI port is unavailable?
Distinguish unsupported browser access, denied permission, an empty input list and a disconnected selected port. Follow the device's ordinary connection instructions without changing browser protection flags. If the browser cannot expose this input, the page leaves that limitation visible instead of guessing that the hardware passed.