Keyboard & Key Switch Test

The most common cause of an isolated dead key is physical debris, dust, or hair lodged beneath the keycap. Carefully remove the keycap (if using a mechanical keyboard) and clean the switch with compressed air. For laptop keyboards, gently brush around the scissor switch.

If pressing "Q" produces "A" or "Z" produces "W", your operating system is set to a different regional software layout (such as French AZERTY or German QWERTZ). Open Windows Settings > Time & Language > Typing or macOS System Settings > Keyboard > Input Sources and select your preferred layout.

Sticky keys are frequently caused by dried liquid spills or damaged return springs. Disconnect the keyboard immediately, clean the affected switch with 90%+ isopropyl alcohol, allow it to dry completely, and verify your OS repeat delay settings in Keyboard Accessibility.

This behavior is caused by hardware matrix limitations known as low Key Rollover (2KRO / 6KRO) found on budget membrane keyboards. It is a hardware design characteristic rather than a defect. Mechanical keyboards featuring N-Key Rollover (NKRO) allow unlimited simultaneous inputs.

Replace or recharge the keyboard batteries and eliminate 2.4 GHz radio interference by moving USB 3.0 external drives and metal objects away from your Bluetooth adapter. If using a wireless USB dongle, plug it into a front-facing port closer to the keyboard.

No web-based test can definitively prove a hardware switch is dead. The browser can verify with complete certainty when a key event is detected. However, if a key never fires, JavaScript cannot distinguish whether the switch is physically broken or whether you simply haven’t pressed it yet. If a key consistently fails to register after multiple presses across different applications, that strongly indicates a hardware or connection issue.

Certain keys are intercepted by your operating system window manager or browser before webpage scripts ever receive the event. On Windows, pressing the Windows key invokes the Start menu, preventing the browser from receiving the keyup event. Similarly, F11 toggles browser fullscreen and PrintScreen triggers OS screenshot tools. This is normal browser behavior and does not mean your key is broken.

Web browsers report two distinct values for every keystroke: `event.code` (which represents the physical switch location on the keyboard regardless of language) and `event.key` (which represents the character produced by your operating system layout). Our visual matrix tracks physical positions so the test works on any layout (QWERTY, AZERTY, Dvorak), while the Live Typing Echo box lets you verify that the correct characters are produced.

Key Rollover refers to how many keys your keyboard can register simultaneously. Many standard membrane keyboards feature 2-key or 6-key rollover and suffer from "ghosting" (where pressing certain combinations drops additional keys). Gaming and mechanical keyboards frequently support N-Key Rollover (NKRO), allowing unlimited simultaneous keypresses. You can test your keyboard’s rollover capacity by holding down multiple keys at once and seeing how many light up.

On-screen software keyboards on iOS and Android use predictive text and Input Method Editors (IMEs). They often do not generate standard physical hardware key codes (`event.code`) or standard keyup events until a word suggestion is accepted. For an accurate hardware switch test, connect a physical USB or Bluetooth keyboard.

No. DeviceChecker operates on a strict client-side privacy model. All keydown and keyup events, as well as text in the Live Typing Echo box, are processed entirely inside your local browser memory. No keystrokes, key logs, or text are ever transmitted across the network.