🎹 Web MIDI navigator.requestMIDIAccess — zero libraries

Plug in a MIDI keyboard (or drum pad, or DJ controller) and the browser hands you the raw protocol: every key press arrives as three bytes. This page lights the on-screen piano from your hardware and synthesizes the sound with Web Audio. No keyboard? The on-screen keys are mouse-playable.

Works in Chromium browsers (Chrome, Edge, Arc, Brave…). Click keys below either way.

Last note

—

Velocity (how hard you hit it)

—

Raw MIDI bytes — the actual wire protocol

[status, note, velocity] messages appear here…

The whole hookup: navigator.requestMIDIAccess(), then every input fires midimessage events with a 3-byte payload. A protocol from 1983, live in a web page.
← Plain JS