Press a button first: browsers hide the pad until you do
If you plugged in a controller, opened our gamepad test and it keeps saying 'No controller detected', press any button on the pad before assuming something is broken. The browser's Gamepad API does not announce connected controllers to a web page straight away. A controller only becomes visible to the page after you press a button on it while that page is in front of you.
This is deliberate, not a bug. The list of devices attached to your computer could be used to help identify you, so browsers keep controllers hidden from websites until you actively use one. Every browser game and every online tester behaves the same way for that reason. Moving a stick is not always enough to trigger it, so press a face button such as A or X to be sure.
Focus matters too. If the test page is in a background tab, or another window is active, the page will not receive the input even though you pressed a button. Click an empty part of the page to focus it, then press again. If there is still no response, the problem is further down the chain, and the steps below work through it in order.
Wired: a charge-only cable is the most common culprit
Not every USB cable carries data. Many of the cables bundled with power banks and small gadgets contain only the power wires and no data lines at all. With one of those, the controller's charging light comes on, yet the PC never sees a device. If your pad charges but is not detected, suspect the cable before anything else.
Checking is easy. Use the same cable to connect a phone to the PC and see whether file transfer works, or swap in a cable you know carries data. On Windows, listen for the device-connected sound when you plug in. Silence means the PC is supplying power but is not seeing any device on the other end.
Try a different port as well. Front-panel ports and unpowered hubs can have marginal contact or power, and plugging straight into a rear motherboard port fixes more cases than you would expect. Also note that some controllers can be set to keep sending input wirelessly even while a cable is attached for charging, so check your pad's manual for a wired communication setting.
Bluetooth: pairing mode and stale pairings
A controller only appears in your PC's Bluetooth search while it is in pairing mode. On an Xbox controller, hold the small pair button on the top edge until the Xbox logo flashes rapidly. On a PlayStation controller, hold the PS button together with Share (Create on the DualSense) until the light bar flashes quickly. On a Switch Pro Controller, hold the small sync button next to the USB port on top.
If it used to work and suddenly will not connect, a stale pairing is the usual cause. A controller remembers the last device it paired with, so if you have since used it with a console or another computer, the entry still listed on your PC is no longer valid. Remove the controller from your operating system's Bluetooth settings and pair again from scratch. A console switched on nearby can also grab the controller first, so power it off while you pair.
There are hardware limits to be aware of. Some early Xbox One controllers have no Bluetooth at all and need the dedicated wireless adapter or a cable. A Bluetooth dongle tucked behind a metal desktop case, or sitting right beside a USB 3.0 device, can suffer interference and dropouts, so move it to a front port or onto a short extension lead. If wireless stays flaky, connect by cable first to confirm the pad itself is healthy.
Detected but the buttons are wrong: XInput, DirectInput and Steam Input
On Windows, controllers speak one of two dialects. XInput is modelled on the Xbox controller layout, while DirectInput is the older, generic scheme. Browsers remap controllers they recognise into a standard layout, but an older or generic pad gets passed through with whatever button and axis numbers the device reports. That is why buttons can appear in a strange order, or the triggers show up as an axis instead of buttons. If your pad has an X/D switch or a mode button, set it to X for XInput and reconnect.
If Steam is running, Steam Input may be intercepting the controller. Steam reads the pad and re-emits it as a virtual controller or as keyboard and mouse input. Typical side effects are the stick moving your mouse cursor on the desktop, or other programs seeing two controllers or an unexpected layout. To rule it out, exit Steam completely from the system tray and test again. If that fixes it, adjust Steam Input for that controller type, or the desktop configuration, in Steam's controller settings.
Wrapper tools such as DS4Windows work on the same principle. They present a PlayStation controller as a virtual Xbox controller, and to avoid double inputs they offer an option to hide the real controller from other programs. With it enabled, the browser sees only the virtual Xbox pad, and if the hiding stays active after the tool is closed, the controller can seem to vanish everywhere. When you are troubleshooting, start with all such tools closed.
Check at the operating-system level: Windows, macOS, Linux
Whether this is a browser problem or a whole-PC problem is settled by checking the operating system. On Windows, press Win+R and type joy.cpl to open 'Set up USB game controllers'. If the pad is listed and its Properties page reacts to buttons and axes, the hardware and driver are fine and the issue lies with the browser or a remapping tool in between. If it is not listed at all, go back to the cable, port and pairing steps. Look in Device Manager for an unknown device with a warning icon while you are there.
Recent versions of macOS support Xbox, PlayStation and Switch Pro controllers over Bluetooth out of the box, and the Game Controllers section of System Settings shows what is connected. Wired support has historically been patchier depending on the controller, so if a cable gets you nowhere, try Bluetooth. On Linux, drivers for the major controllers ship with the kernel and usually just work, but input device permissions, or the sandbox around a browser installed via Flatpak or Snap, can leave the browser alone unable to see the pad. Comparing against a browser installed from your distribution's own packages is a quick way to confirm that.
Browsers differ as well. Chromium-based browsers such as Chrome and Edge have the broadest controller recognition and standard-layout remapping. Firefox and Safari support the Gamepad API too, but the layout of a particular pad, and whether vibration is available, can differ. If results look odd in one browser, check another, and make sure the browser is up to date, which by itself resolves some cases.
Once it is detected: what to test, and isolating the faulty part
With the pad showing up, give it a full check. Our test displays every button and keeps a count of how many you have confirmed, so press each one in turn, including the D-pad, the stick clicks (L3 and R3) and the bumpers. Squeeze LT and RT slowly and watch the value climb smoothly from 0.00 to 1.00. A trigger that never reaches 1.00 at full pull, or does not fall back to 0.00 when released, has a sensor problem.
For the sticks, let go and see whether the dot rests inside the dashed deadzone ring, which is set at 0.08. A dot that settles outside the ring or creeps to one side is stick drift, and our stick drift guide covers the causes and remedies in detail. Try the vibration test button as well. If it reports 'unsupported', nothing is broken. It means this combination of browser and controller does not offer vibration, so try another browser or connection method.
If the controller still will not appear anywhere, change one thing at a time. Swap only the cable. Then only the port. Then switch between wired and wireless. Finally, connect the same pad to a different PC, a console or a phone. If it works elsewhere, the fault is in the original PC's settings or software. If it is dead with every cable and every device, the controller itself has most likely failed. Changing several things at once leaves you unable to say which one mattered, so keep to the order.