WebUSB: Browser Support, Features, Limitations

What is WebUSB?

WebUSB is a JavaScript API that gives a web page low-level access to USB devices through the navigator.usb object, without any native driver or browser plugin. The Web Platform Incubator Community Group at the W3C edits the spec, and Reilly Grant at Google is the editor. The API supports control, interrupt, bulk, and isochronous transfers, so a single page can reflash an Arduino, drive a receipt printer, or read raw sensor data from custom hardware.

Which browsers does WebUSB support?

Chromium-based browsers ship WebUSB on desktop and Android, while Firefox, Safari on macOS, and Safari on iOS leave it out, so global browser support sits at about 76% as of April 2026.

What are the key features of WebUSB?

WebUSB exposes the full USB protocol stack to a web page, while the browser keeps the user in control of every device handshake. The headline features cover device selection, raw transfers, and event-based device updates.

• navigator.usb.requestDevice: Pops a browser-supplied device chooser on a click. The user picks a device from a filter list of vendor IDs, product IDs, USB classes, and serial numbers, and the page only sees the device the user selected.
• navigator.usb.getDevices: Returns the list of devices the user has already approved for the origin. The page never gets a free pass to enumerate hardware in the background.
• USBDevice.open and USBDevice.close: Open and close the device handle. Only one tab can hold the handle at a time, so the API surfaces a clear lifecycle and avoids contention with native drivers.
• selectConfiguration and claimInterface: Pick the active USB configuration and claim an interface for exclusive use. Both calls are mandatory before any data transfer.
• controlTransferIn and controlTransferOut: Send and receive control transfers on endpoint zero, the standard channel for USB setup packets and vendor-specific commands.
• transferIn, transferOut, isochronousTransferIn, isochronousTransferOut: Run bulk, interrupt, and isochronous transfers on any claimed endpoint. Each call takes a Uint8Array buffer and returns a USBTransferResult.
• connect and disconnect events: Fire on the navigator.usb object when an approved device is plugged in or unplugged. Pages can react to USB cable changes without polling.
• USBDevice.forget: Revokes the page's permission for that device, available from Chrome 101. The next requestDevice call must show the chooser again.
• HTTPS and user gesture only: WebUSB only runs in a secure context, and requestDevice only fires inside a real user activation. Both rules are enforced by the browser, not the page.

How do you connect to a USB device with WebUSB?

You connect to a USB device by feature-detecting navigator.usb, calling requestDevice from a user gesture, opening the returned device, selecting a configuration, and claiming an interface. Every step has to run on a click or keypress because requestDevice requires user activation.

Use the filters argument to narrow the chooser to your hardware. A filter can match vendorId, productId, classCode, subclassCode, protocolCode, and serialNumber. The browser shows the user every connected device that matches at least one filter.

Paste this snippet into the DevTools console of Chrome, Edge, Opera, or Samsung Internet on Android. Click anywhere on the page once and the device chooser opens.

// Paste this into the DevTools console to confirm WebUSB support and request a device.
if ("usb" in navigator) {
  console.log("WebUSB is available.");

  document.body.addEventListener("click", async () => {
    try {
      const filters = [{ vendorId: 0x2341 }]; // example: any Arduino USB device
      const device = await navigator.usb.requestDevice({ filters });

      await device.open();
      if (device.configuration === null) {
        await device.selectConfiguration(1);
      }
      await device.claimInterface(0);

      console.log("Opened device:", device.productName, "by", device.manufacturerName);
    } catch (error) {
      console.log("WebUSB request failed:", error.message);
    }
  }, { once: true });
} else {
  console.log("WebUSB is not supported in this browser.");
}

If the console prints "WebUSB is not supported in this browser", you are running Firefox, Safari, or a non-Chromium mobile browser. Fall back to a native helper app or a Trusted Web Activity for those visitors.

What are the known issues with WebUSB?

WebUSB lives in Chromium and skips two of the three browser engines, so the painful edge cases land on Firefox refusal, the Safari and iOS gap, the user-gesture rule, and the platform-level USB blocklist.

• Firefox calls WebUSB harmful: Mozilla flags WebUSB as harmful in its standards position. Sites that need USB access on Firefox must ship a native helper or guide users to Chrome, Edge, or Opera.
• No Safari, no iOS, no iPadOS: Safari on macOS, iPadOS, and iOS lack WebUSB and the WebKit position lists the spec as opposed. iPad and iPhone visitors need a native app or a sidecar tool, since there is no flag to enable.
• Built-in USB blocklist: Chrome blocks access to HID keyboards, mice, FIDO authenticators, smart cards, USB audio class devices, and any device whose interface class sits on the WebUSB blocklist. The page cannot override the list, so kiosk and authentication use cases fall back to native code.
• requestDevice must run on a user gesture: Chrome throws DOMException "Must be handling a user gesture" if you call requestDevice from a setTimeout, fetch callback, or page-load handler. Always wire it to a click or keypress.
• Windows needs a WinUSB driver: On Windows, the device must bind to the WinUSB.sys driver before Chrome can open it. Vendors ship a Microsoft OS 2.0 descriptor or use a tool like Zadig to swap the driver.
• One tab owns the device: Once a tab calls open and claimInterface, no other tab or native process can talk to the device until the tab calls close or is destroyed. Plan your UX so users do not race two pages onto the same hardware.
• No background access: Service workers and background pages cannot call requestDevice, and a page loses the device handle when the tab is discarded. Long-running USB sessions must keep the foreground tab alive.
• HTTPS or localhost only: WebUSB refuses to run on plain HTTP origins. Local development needs http://localhost or a self-signed HTTPS certificate, since file:// pages also fail the secure-context check.

In my experience, the trickiest failure is the Windows driver step. A board that works out of the box on Linux and macOS opens fine in Chrome, but the same board on Windows throws "Unable to claim interface" until the user runs Zadig and swaps the driver to WinUSB. Ship a one-page driver guide alongside any WebUSB product, or your Windows users will assume the page is broken.

Citations

All WebUSB version numbers and platform notes in this guide come from these primary sources:

• MDN Web Docs - WebUSB API: developer.mozilla.org/en-US/docs/Web/API/WebUSB_API
• MDN Web Docs - USB interface: developer.mozilla.org/en-US/docs/Web/API/USB
• WICG - WebUSB API editor's draft: wicg.github.io/webusb
• WICG - WebUSB GitHub repository: github.com/WICG/webusb
• Chrome for Developers - Access USB Devices on the Web: developer.chrome.com/docs/capabilities/usb
• Chrome for Developers - Use WebUSB in Chrome Extensions: developer.chrome.com/docs/extensions/how-to/web-platform/webusb
• Chrome Platform Status - WebUSB feature: chromestatus.com/feature/5651917954875392
• Chrome Platform Status - USBDevice forget method: chromestatus.com/feature/5630369791901696
• Wikipedia - WebUSB: en.wikipedia.org/wiki/WebUSB
• Mozilla Specification Positions: mozilla.github.io/standards-positions
• WebKit - Standards Positions: webkit.org/standards-positions
• Microsoft Learn - Microsoft OS 2.0 Descriptors: learn.microsoft.com/en-us/windows-hardware/drivers/usbcon/microsoft-os-2-0-descriptors-specification