Plug in (or pair) your controller and press any button — it appears below with live button and stick readouts. The full tester draws your controller's diagram, measures stick drift at rest, and sweeps the full range of each stick.
Drift is the stick reporting motion while untouched — worn potentiometers or debris under the module. At rest, a healthy stick reads within ±0.05 of center; persistent readings beyond ~0.1 will move your camera in games that use a small dead zone. Dead zone is the radius games ignore around center precisely to mask small drift; heavy drift outgrows it. Hall-effect sticks (magnetic, no contact) don't wear this way, which is why they're taking over on premium and repair-friendly pads.
If your pad connects but buttons map strangely, that's usually a mapping profile issue: browsers expose a "standard" layout when they recognise the pad and raw indices when they don't. The full tester shows both the mapping type and every raw axis and button, so you can tell a broken button from an unmapped one.
Press a button first — browsers deliberately hide gamepads until an input, and the page must be focused (click the page, then press). Bluetooth pads also need to be in pairing/connected mode. If it still fails, try a cable.
At rest, within ±0.05 of center is healthy. Beyond ~0.1 you'll fight the camera in most games. Our full tester samples the stick at rest for 5 seconds and gives you the number.
Sometimes: isopropyl alcohol around the stick base fixes debris-caused drift; games and some system menus let you raise dead zones. Worn potentiometers need a module swap — or a Hall-effect replacement module if your pad has one.