Check Web MIDI availability for a hardware inventory

A hardware inventory can say a MIDI keyboard is connected, but that does not tell you whether a browser can access it. Browser support, site permission, and the connection itself are separate parts of the check.

Use Browser Info to check whether the browser reports Web MIDI support, then use MIDI Test to see whether it can detect and receive input from a connected controller. This helps you record what is available on that computer, without treating a browser test as a complete system inventory.

Check Web MIDI and the connected device

1. Open Browser Info and review the reported supported features and permissions. Look for a Web MIDI or MIDI entry, and note the browser name and version for your inventory.
2. Connect the MIDI keyboard or controller directly to the computer if possible. Turn it on, and wait for the operating system to finish recognizing it.
3. Open MIDI Test. If the browser asks to access MIDI devices, allow access for this test page. The browser may show a permission prompt or a device list.
4. Press several keys, including one in a different octave. If the controller has knobs, pedals, or pads, move or press one of those too. Check whether the test receives the input and reports the device or MIDI messages.
5. Record the result with the computer model or asset ID, operating system, browser and version, Web MIDI support, permission outcome, connected device name, and whether input arrived. Note any controls you tested.

For a useful comparison, use the same controller and cable when checking another computer. Keep the browser version and permission result in the notes, since a missing device does not necessarily mean the hardware is absent.

What the result means

Web MIDI is reported and the controller sends input

The browser supports Web MIDI, the page has access, and the connected device is sending data that the test can receive. Add the controller to the inventory as available to this browser on this computer. This does not prove that every MIDI control works, so test the keys, knobs, pedals, or pads that matter for the inventory.

Web MIDI is reported, but no controller appears

The browser may support the feature while the operating system does not currently expose a MIDI device to it. Check that the controller is powered, connected, and recognized by the computer. Also confirm that the page has permission. Web MIDI availability by itself does not identify installed or disconnected hardware.

A device appears, but playing it produces no input

The browser can see a device, but the test did not receive the control events you tried. Check that you are using the correct device if more than one is listed. Try a different key or control, and reconnect the controller before recording it as nonresponsive.

Web MIDI is not reported or the test cannot access it

This points to a browser, permission, or compatibility limit, not necessarily a missing controller. Safari does not support MIDI Test. Try a compatible desktop browser, then check again before concluding that the computer cannot use the device.

The test receives messages, but the device name is unclear

Some controllers use a generic name, and a single physical controller can expose more than one MIDI port. Record the exact name shown by the test along with the manufacturer and model from the device label. Do not assume that a port name identifies a unique piece of hardware.

How to fix missing MIDI access

1. Check the cable and power. Connect the controller directly to the computer, rather than through a hub, and try another known data-capable USB cable if you have one. A charge-only cable can power a device without carrying MIDI data.
2. Allow access for the test page. If the browser shows a MIDI permission request, grant it. If you previously blocked access, open the site permissions from the icon beside the address bar, change the MIDI permission if that option is available, then reload the page.
3. Check that the computer recognizes the controller. On Windows 11, open Start › Device Manager and check for a device entry or warning under the relevant USB or audio device categories. On macOS, open Applications › Utilities › Audio MIDI Setup, then choose Window › Show MIDI Studio to see whether the system lists the device.
4. Close other MIDI software. Quit music applications or other browser pages that are using the controller, then reconnect it and try the test again. A device can behave differently when another program has opened its MIDI connection.
5. Try another supported desktop browser. Recheck Browser Info and MIDI Test in that browser. If Web MIDI works there, record a browser compatibility difference rather than marking the hardware as missing.
6. Restart the computer. If the operating system does not list the controller after reconnecting it, restart and test again. If it remains absent, inspect the device, cable, and port on another computer before deciding whether the controller needs repair.

What this check cannot inventory

Web MIDI is a browser interface for exchanging MIDI messages with devices that the browser can access. It is not a full hardware scan. It may not show disconnected equipment, devices hidden by operating-system or browser restrictions, or every port and capability exposed by specialist software.

For an inventory, separate these facts in your notes: the computer physically has a controller, the operating system recognizes it, the browser supports Web MIDI, the page has permission, and the test receives messages. That wording makes a failed browser check useful without wrongly labeling working hardware as defective.