Web USB is a browser API that allows web applications to communicate with USB devices directly. This console uses the navigator.usb API to request device access, claim interfaces, and perform data transfers (control, bulk, interrupt, and isochronous).

Once connected, you can send raw hex data, ASCII commands, or use the preset control transfers to fetch USB descriptors, all from your browser — no drivers or native apps needed.

Web USB is supported in Chromium-based browsers:

• Google Chrome 61+ (desktop & Android)
• Microsoft Edge 79+
• Opera 48+
• Brave, Vivaldi, and other Chromium browsers

Not supported: Firefox, Safari (iOS/macOS). The page must also be served over HTTPS or localhost for the API to work.

This is the most common Web USB issue. It happens when the operating system kernel has already claimed the interface. Solutions:

• Linux: Create a udev rule to unbind the kernel driver, e.g.: SUBSYSTEM=="usb", ATTR{idVendor}=="xxxx", MODE="0666" or use usbguard.
• Windows: Use Zadig tool to replace the driver with WinUSB for that specific device.
• macOS: Use IOUSBHostInterface or consider using a different interface if available.
• Try selecting a different interface number if your device exposes multiple interfaces.

• Control Transfer: Used for device configuration and standard USB requests (GET_DESCRIPTOR, SET_CONFIGURATION, etc.). Bidirectional, structured with setup packet + optional data stage.
• Bulk Transfer: High-volume, reliable data transfer. Used by storage devices, printers. Error-checked with retry. No guaranteed timing.
• Interrupt Transfer: Low-latency, small data packets. Used by HID devices (keyboard, mouse). Guaranteed maximum latency.
• Isochronous Transfer: Stream-oriented, fixed bandwidth. Used for audio/video. No error retry — data integrity is sacrificed for timing.

USB responses are typically in little-endian byte order. For example, a Device Descriptor response (18 bytes) contains:

• Bytes 0-1: bLength, bDescriptorType (should be 18, 01)
• Bytes 2-3: bcdUSB (USB version, e.g., 0x0200 = USB 2.0)
• Bytes 4-6: bDeviceClass, bDeviceSubClass, bDeviceProtocol
• Bytes 8-9: idVendor (Vendor ID)
• Bytes 10-11: idProduct (Product ID)

This console displays responses in both hex and ASCII format for easy reading.

Generally, no permanent damage can occur from standard USB requests and data transfers. However:

• Sending malformed data to custom firmware could cause unexpected behavior (device hang, requiring a power cycle).
• Always verify the endpoint direction — writing to an IN endpoint or reading from an OUT endpoint will fail.
• Respect the packet size (wMaxPacketSize) — exceeding it may cause data truncation.
• For production or sensitive devices, always test in a controlled environment first.

Web USB has strong security protections:

• Device selection requires explicit user gesture (click) — websites cannot silently connect.
• The browser shows a permission prompt listing available devices.
• Only the selected device is accessible; other USB devices remain hidden.
• Sites must be served over HTTPS (or localhost).
• Users can revoke permissions at any time via browser settings.
• No data leaves your browser — all communication is local between your browser and the USB device.