USB
USB devices are everywhere — keyboards, mice, storage, cameras. Scan connected USB devices, read device descriptors, and troubleshoot connection issues using WebUSB.
USB Device Check
usb device check, usb diagnostic, usb scanner
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Open Tool →USB Device Info
usb device info, vid pid lookup, usb device identifier
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Open Tool →Printer Test
printer test, printer tester, test page
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Open Tool →USB
USB devices are everywhere — keyboards, mice, storage, cameras. Scan connected USB devices, read device descriptors, and troubleshoot connection issues using WebUSB.
Privacy First usb Testing Tools on usbRecognized run entirely in your browser using secure Web APIs. No software download, no installation, no data upload — your privacy is 100% protected. Simply click on a tool above to start testing.
Some tools in this category are available now (marked with ✓). Others are coming soon — each coming soon page includes a detailed preview of what the tool will do and how you can test your hardware in the meantime.
What WebUSB Can and Cannot See
A browser can only reach a USB device through an explicit permission prompt, and only if the device exposes an interface the browser is allowed to claim. Devices that the operating system has already bound to a protected class driver, such as keyboards, mice and mass storage, are deliberately blocked from web access because handing them to a web page would be a security hole. This restriction explains most of the confusion about a USB test that appears to see nothing.
For the devices that are reachable, the browser can read the device descriptor, the configuration and interface descriptors, the vendor and product identifiers, and the reported link speed. That is a meaningful amount of diagnostic information. It is enough to identify an unknown device, to confirm whether it enumerated correctly, and to tell whether it is running at the speed you expect.
What the browser cannot do is issue class-specific commands to arbitrary devices, read data from a device it has not been granted, or inspect the electrical layer. A device that fails to enumerate at all will not appear in the list, because enumeration happens below the layer the browser can observe. That negative result is itself informative: it moves the investigation from software to cabling, ports and power.
Reading USB Descriptors: VID, PID, Class, and Speed
The vendor identifier and product identifier are the two numbers that identify a device to the operating system. The vendor identifier is assigned to a manufacturer, and the product identifier is chosen by that manufacturer for a specific product. Together they are how a driver is matched, and looking them up is the fastest way to identify a device whose label has worn off or whose name is reported as unknown.
Device class describes the kind of device at a broad level, and interface class describes the specific function of each interface. A composite device such as a headset declares one interface for audio and another for the control buttons, and each interface carries its own class. This is why a device can appear in the list more than once, and why a headset can partially work when only one of its interfaces has been claimed by the operating system.
Reported speed is the negotiated link speed rather than the maximum the device supports. A device capable of a high-speed link will fall back to a lower one if the cable, the port or the hub does not support it. A device that reports a lower speed than its specification is not necessarily faulty; the more likely explanation is a cable that is only wired for the lower rate, which is common with charging cables sold without a data rating.
A Triage Order for Devices That Are Not Recognised
Work from the outside in. Start with the cable, because a charge-only cable is the most common cause of a device that works elsewhere and fails here. Then change the port, preferring one directly on the machine over one on a hub, since a hub that cannot supply enough current will cause intermittent enumeration that looks like a software fault. Only then move to drivers.
If the device enumerates and then disappears, suspect power rather than data. A device that draws more current than the port can supply will enumerate successfully and then drop off when it begins to work. External drives and bus-powered hubs are the usual examples. A powered hub resolves this class of fault, and confirming it costs nothing.
If the device never appears in the list even when other devices do, the fault is below the browser. Check whether the device appears in the operating system device manager at all. A device absent from the operating system cannot be seen by a browser, and no amount of web-based testing will change that. This is the point at which the investigation moves to hardware and drivers.
Printer Checks Over USB
A printer presents a specific diagnostic problem because most of its behaviour does not happen over the USB link. The page description language, the colour management and the nozzle health are all handled inside the printer, so a printer that communicates perfectly can still print badly. Separating the connection from the output is the first step in diagnosing a printer complaint.
Connection faults show up as a printer that is reported as offline or that spools a job and never prints. These are worth checking at the USB layer, because a printer that drops off the bus when it wakes from sleep will look exactly like a driver problem. A printer that enumerates reliably and still produces poor output has a print quality problem, not a connection problem.
Print quality faults have their own short list of causes. Horizontal white bands usually indicate clogged nozzles in the print head. Colour shifts across a page usually indicate a partially empty cartridge or a misaligned head. Repeated vertical marks at a regular spacing usually indicate a roller or a scratch on the drum. A test page that exercises each of these separately is more diagnostic than printing a document and judging it as a whole.
USB FAQ
What does a USB device check actually do?
It enumerates the USB devices the browser is permitted to reach, then reads their descriptors: vendor and product identifiers, device and interface classes, and the negotiated link speed. It reports what the operating system has already accepted, which makes it useful for identifying an unknown device and for confirming that a device enumerated at the speed you expect rather than falling back.
Why can my browser only see some USB devices?
Browsers deliberately block access to device classes that would be dangerous to expose, which includes keyboards, mice and mass storage. A web page that could claim your keyboard could log every keystroke, so the restriction is a security boundary rather than a bug. Devices in those classes still work normally; they simply cannot be inspected from a web page.
What is a VID and PID and why do they matter?
The vendor identifier is a number assigned to a hardware manufacturer, and the product identifier is chosen by that manufacturer for a particular product. The operating system uses the pair to decide which driver to load. They matter because looking up the pair identifies a device precisely, even when the reported name is generic or the label has worn off.
My USB device is not recognised. Where do I start?
Start with the cable and the port, not with drivers. A charge-only cable carries power but no data, and it is the single most common cause. Move the device to a port directly on the machine rather than on a hub, and try another machine if one is available. If the device is absent from the operating system device manager as well, the fault is below the browser entirely.
How can I tell if a device is running at USB 2.0 or 3.0 speed?
The check reports the negotiated link speed, which is what the device and the host actually agreed on. A device that supports a faster link but reports a slower one has fallen back, most often because of the cable. Cables rated only for the lower rate are widely sold and are often bundled with devices that can run faster, so the cable is the first thing to swap.
Why does my printer show as offline?
An offline printer usually has a connection or power-management cause rather than a driver cause. Check whether the printer disappears from the USB bus when it enters sleep, and whether it enumerates reliably when you turn it on. If the connection is stable and the printer still reports offline, the fault is in the print queue or the driver rather than the cable.
Is it safe to grant a website access to a USB device?
It is safe when you recognise the site and understand what it does with the device, because the permission is scoped to the specific device you select rather than to all USB devices. The browser shows an explicit picker, and the page can only claim the interface you chose. Grant access to a diagnostic page you trust, and revoke it afterwards if you prefer.
Can I identify an unknown USB device without installing drivers?
Yes, if the device is in a class the browser can reach. Reading the vendor and product identifiers is enough to look up the manufacturer and model without a driver, because the identifiers are reported by the device itself at enumeration. This is often faster than working through the operating system device manager, which may group unknown devices under a generic heading.