Troubleshooting
Controller not detected
Most of the time, a controller that doesn't show just hasn't been pressed yet. Go through these in order.
Press a button
A browser shows a pad to a page only once it has been used there: Chrome after a press or a push of a stick on any pad, Firefox after input from that pad, and Safari after a press, and only while its window is in front. Press a face button with the page open.
Check the connection
Over USB, try another cable, since many only charge, and another port. Over Bluetooth, check that the pad is paired in your system's Bluetooth settings and turned on, and that its battery isn't flat. With a dongle, check that the pad is set to use it, as some pads switch between their dongle and Bluetooth. On a Mac, a pad in its XInput mode shows only from macOS 15, and not every one then: switch it to another of its modes.
Read more in Connecting a controller
Apps that take the controller
An app that remaps controllers, such as DS4Windows, reWASD or Steam's own controller settings, can hide a pad from the browser, or show it as another, such as an Xbox 360 controller. Close it, or turn its hiding off, and try again. WebHID can't open a pad another program holds, either.
The browser
PadBench needs Chrome or Edge 123, Safari 17.5 or Firefox 120, or later, and says so in an older browser. Firefox with resist fingerprinting on, as Tor Browser and LibreWolf have it, shows no pads at all. Safari sees only the pads Apple supports, so most arcade sticks and generic pads never show there; and on Windows, Firefox can stop reading a pad while another app is in front.
Read more in Safari, iPhone and iPad
A pad the browser doesn't list
In Chrome and Edge on a computer, + after the controller tabs opens the browser's list of controllers, where a pad the Gamepad API doesn't list can be chosen and read through WebHID. If PadBench finds no control it can read in its reports, it still shows how often it reports and the bytes it sends.
A pad that stays, or shows twice
In Chrome and Edge on Windows, a Bluetooth pad you've turned off can stay, holding what it last held, such as the PS button, even after a reload, since Windows keeps the paired device. The same device can show as a second pad that never changes beside the pad on its cable; PadBench hides it once the real pad is used. Read through WebHID, a DualSense that has gone quiet is dropped within two seconds.