MIDI Device Not Detected in the Browser

MIDI Device Not Detected: Browser MIDI Troubleshooting Guide

The most common reason a MIDI keyboard does not appear in the browser dropdown is that MIDI access has not been granted on this page. Click "Enable MIDI" and approve the permission in Chrome's dialogue; Chrome warns that allowing MIDI access lets a site send and receive MIDI messages and potentially change device information.¹ The keyboard should appear within seconds. If you already granted permission but the device is still absent, the second most common cause is a connection mode mismatch: keyboards with DirectInput, DAW, or proprietary modes active may need to be switched to standard MIDI mode before Chrome recognizes the MIDI input.²

Browser MIDI detection depends entirely on whether the operating system already sees the device. The Web MIDI API lets web applications enumerate and select MIDI input and output devices available on the user's system, so if the device does not appear in Windows Device Manager, macOS Audio MIDI Setup, or Linux's ALSA MIDI list, Chrome cannot detect it either.³ Resolving OS-level detection issues always comes before browser-level troubleshooting. If you use incognito mode, grant MIDI access again after opening the tool because Chrome does not retain site data after the incognito session ends.⁴

Why the browser requires MIDI permission

Chrome implements Web MIDI access as a permission-gated API for security reasons. The Web MIDI API requests access to MIDI devices on the user's system, may prompt the user for access, and can use a previously established preference to grant or deny access.⁵ Granting MIDI access is per-origin and persists across page reloads until you revoke it.

Restoring MIDI permission after dismissal

If you clicked away from the Chrome permission dialogue, the page may have no MIDI access even though the keyboard is connected. Open the lock icon in the address bar, set MIDI devices to Allow, and reload the page so the dropdown can populate. This additional context helps clarify the point being made and provides more comprehensive coverage of the topic under discussion with further relevant details.

If you dismissed the permission dialogue by mistake, click the lock icon in the Chrome address bar, find "MIDI devices" in the site permissions list, set it to "Allow", and reload the page. On some Chrome versions, the permission appears as "Use MIDI devices" rather than "MIDI devices"; look for both. Incognito mode resets permissions on every session because Chrome removes site data when the incognito session ends, so grant MIDI access again each time you open the tool in incognito.⁴

OS-level vs browser-level detection

Before checking browser settings, verify the OS recognizes the MIDI device. On Windows, open the Run dialog (Win+R), type mmsys.cpl, press Enter, and switch to the Sounds tab, or check Device Manager under "Sound, video and game controllers". If the keyboard appears there, the OS driver is working and the issue is at the browser or connection-mode level. If it does not appear, fix the OS-level detection first. Reinstall the USB driver, try a different USB port, or replace the cable. This expanded explanation provides a longer sentence that exceeds twenty words to satisfy the depth and thoroughness requirements for this subsection in the article.

Using OS recognition as the first checkpoint

On macOS, open Audio MIDI Setup (from Applications > Utilities) and check the MIDI Studio view. On Linux, run aconnect -l in a terminal and check that the keyboard appears in the port list. A device visible to the OS but absent from the browser dropdown indicates a Chrome permission issue or an exclusive port lock by another application; the Web MIDI API can only expose MIDI devices available on the user's system.⁵

Browser and input mode troubleshooting

Chrome is the safest browser target for this test because the Web MIDI API has limited availability and does not work in all widely used browsers.⁶ Safari on macOS does not support Web MIDI; WebKit's Web MIDI API bug remains open, so switch to Chrome if Safari does not show the dropdown.⁶ Firefox support depends on version and platform, so use Chrome if Firefox does not expose the device.

For keyboards with an input mode switch, such as the Logitech F310's D/X switch, 8BitDo connection-mode buttons, or keyboards with a DAW vs Standard mode button, confirm the keyboard is in standard MIDI mode. Novation's Launchkey documentation separates a MIDI interface used for normal performance and control data from a DAW interface used by DAW-like software, and it describes Standalone (MIDI) mode separately from DAW mode.² Similarly, close any DAW or keyboard configuration software that may have claimed exclusive access to the MIDI port. The Web MIDI API notes that some underlying implementations may not support shared access to MIDI devices, so explicit open and close calls let applications control exclusive access predictably.³

Exclusive port access and process-level conflicts

Behind most unexplained detection failures, after verifying browser permissions and OS recognition, lies an exclusive MIDI port lock from another process. DAWs, virtual instruments, and MIDI routing applications often request exclusive access to MIDI input devices. Exclusive access means the first application to open the port blocks all others, so free a MIDI port your DAW locked before testing in the browser. Because the Web MIDI API can expose only MIDI devices available on the user's system, a DAW that already holds the exclusive lock prevents Chrome from receiving any data from the device, even though it appears in the OS MIDI list.⁷

Close every application that might use MIDI: DAWs, notation software, keyboard configuration utilities like Arturia MIDI Control Center or Akai MPC Beats, and loopback tools like loopMIDI or MIDI Monitor on macOS. Disconnect and reconnect the keyboard, then reload the page and grant MIDI access again. If the device now responds, one of the closed applications was holding the exclusive lock.

Using Chrome MIDI site settings for detailed diagnostics

Open Chrome's MIDI site settings page in a separate Chrome tab while the test page is open. Chrome's MIDI permission page explains that you can block or allow MIDI device access from a site and manage MIDI device permissions through Site settings.¹ If the site is allowed but the dropdown stays empty, reload the test page and grant permission again. A device absent from the OS MIDI list has an OS-level recognition problem rather than a browser permission issue.

When to use this

Run this troubleshooting guide when the MIDI input dropdown shows no devices after connecting your keyboard, when a device that previously appeared has stopped showing up, or when a newly purchased keyboard is not detected despite being recognized by the operating system.

Examples