Connect a MIDI device and click 'Start Test' to see real-time MIDI input. Notes will highlight on the virtual piano.
MIDI events will appear here...
Connect your MIDI controller or keyboard before clicking "Start Test". The browser will request permission to access MIDI devices.
Play notes on your MIDI device — they will appear on the virtual piano and in the event log with note name, velocity, and channel info.
The Web MIDI API requires a secure context (HTTPS or localhost). Some browsers may need to enable MIDI support in settings.
MIDI (Musical Instrument Digital Interface) is a communication protocol established in 1983 that allows electronic musical instruments, computers, and other devices to communicate. Unlike audio, MIDI doesn't transmit sound — it sends performance data like which note was pressed, how hard (velocity), and for how long. This makes MIDI files extremely small and fully editable.
MIDI communication uses several message types: Note On/Off — indicates a key press/release with pitch (0-127) and velocity (0-127). Control Change (CC) — handles knobs, faders, pedals, and other controllers. Program Change — switches instrument sounds/patches. Pitch Bend — smooth pitch modulation. Each message is sent on one of 16 channels, allowing multiple instruments on a single connection.
MIDI keyboards are the most common, ranging from 25-key portable controllers to 88-key weighted instruments. Pad controllers (like the Akai MPC) use pressure-sensitive pads for beat-making. Wind controllers mimic brass/woodwind instruments. MIDI guitars translate string vibrations to MIDI data. Modern controllers connect via USB (which is class-compliant — no drivers needed) or traditional 5-pin DIN cables.
The Web MIDI API provides browsers with the ability to interact with MIDI devices directly. It requires a secure context (HTTPS or localhost) and user permission. Currently supported in Chrome, Edge, and Opera — Firefox and Safari have limited support. The API provides real-time access to MIDI input messages, making it possible to build web-based music applications, virtual instruments, and MIDI monitors.
Ensure your MIDI device is connected via USB before clicking Start. Try using a different USB port or cable. Some devices need drivers installed first. The Web MIDI API works best in Chrome, Edge, and Opera. Firefox may require enabling experimental flags.
No. MIDI only transmits performance data (note on/off, velocity, control changes). It's like sheet music for computers — it tells instruments WHAT to play, not HOW it sounds. The actual sound depends on the synthesizer or sampler receiving the MIDI data.
Bluetooth MIDI support varies by browser and OS. On macOS, pair your Bluetooth MIDI device in Audio MIDI Setup first. On Windows, you may need a third-party tool to create a virtual MIDI port. USB MIDI devices are the most reliable option for web-based testing.