A connected controller may work in a game yet remain invisible to a webpage. That does not immediately indicate a fault. Browsers apply privacy and security rules, some expose a gamepad only after a deliberate button press, and another application may hold or transform the device.
Use a simple troubleshooting order that changes one layer at a time.
Trigger browser activation
Open the Gamepad Tester, click the page and press a face button on the controller. Moving a stick alone may not be enough in every browser. The page listens for the standard gamepadconnected event and also checks the current list of exposed devices on each animation frame.
If the controller appears, confirm its reported button and axis counts. A generic mapping can use different numbers than the diagram you expect; raw index changes are still useful even when labels do not match a console layout.
Reconnect in a known state
Close games and controller configuration applications, disconnect the device, wait briefly and reconnect it. For Bluetooth, confirm the operating system still lists it as connected. For USB, use a direct port and a cable known to carry data—not a charge-only cable.
Return to the page and press a button again. Avoid reconnecting several controllers at once because the browser may expose multiple indices and make the active device unclear.
Compare a current browser
Gamepad API behavior and supported device mappings differ among browsers and operating systems. Test a current Chromium- or Firefox-based browser if available. A result in one browser is evidence about that environment, not a universal controller verdict.
Some browser device features require a secure connection. Use https://keymap.io, keep the browser current and avoid copied or embedded versions of the page when comparing results.
Remove competing layers
Steam Input, manufacturer utilities, virtual-controller software and accessibility tools can remap, combine or hide devices. Document the active profile before disabling anything. Close one layer, reconnect and repeat the test.
If a game uses a virtual controller while the browser sees the physical controller, button numbering or axis behavior may differ. That is a mapping difference, not necessarily a broken input.
Check what “detected” means
A device name in the page confirms that the browser exposes a gamepad object. It does not prove every button is wired correctly. Move every axis and press every button. Use the Stick Drift Test only after confirming the expected stick axes move.
Some controllers expose triggers as analog buttons; others use axes. Motion sensors, touchpads, LEDs and vibration are not consistently represented by the standard browser mapping. Their absence in a web tester does not prove those hardware features failed.
When the controller works nowhere
If the operating system, games and multiple browsers all fail to detect the device, try another cable, port and computer before service. Check the manufacturer’s pairing, firmware and reset instructions for the exact model. Avoid installing unknown drivers from unofficial download sites.
For a useful support report, include controller model, wired/wireless mode, operating system, browser version, whether a button press was used for activation, and which other applications detect it. That separates a browser exposure problem from a system-wide connection failure.