Connecting a MIDI keyboard on PC, Mac, iPhone and Android

Bluetooth or USB, and the one trap on each system.

Everything below was tested on a Roland FP-30X, with a Mac over Bluetooth and with an Android phone.

Before anything: one device at a time

A keyboard only talks MIDI to one device at a time. If it is already connected somewhere else, your browser will not see it. Bluetooth pianos reconnect on their own to a device they know: a Mac you used before, a tablet, the piano's own app. Turn Bluetooth off on that device (or close the app) first.

The browser

Chrome, Edge, Opera and Brave work on computers and Android. Firefox works on computers. Safari does not, and no browser on iPhone does. The first time, the browser asks if the site can use MIDI devices: say yes.

Bluetooth

Mac. Don't pair in the normal Bluetooth settings. Open Audio MIDI Setup (Applications → Utilities), then Window → Show MIDI Studio, click the Bluetooth icon and Connect your keyboard. The browser then sees it like a cable.

Android. Android doesn't show Bluetooth MIDI in its Bluetooth settings, and Chrome can't scan for it. Install the free app MIDI BLE Connect, connect the keyboard there, then open the site in Chrome.

iPhone and iPad. iOS browsers have no Web MIDI (they are all Safari underneath). Open the site in the Web MIDI Browser app instead, it adds MIDI support.

Windows. Browsers don't see Bluetooth MIDI on Windows yet. Use a USB cable.

USB

Most keyboards have a square USB port on the back, like a printer. One cable and you are done, no driver needed.

Android: you need an OTG cable or adapter (USB C on the phone side). If nothing happens, pull down the notifications and switch "USB charging" to "MIDI".

iPhone: same as Bluetooth, use the Web MIDI Browser app.