System tool
Keyboard & Mouse Tester
Is a key missing presses? Check the events your browser receives as you press, release, and move the mouse.
Click the test panel before testing keys
EscapeF1F2F3F4F5F6F7F8F9F10F11F12
`1234567890MinusEqualBackspace
TabQWERTYUIOP[ L[ RBackslash
CapsLockASDFGHJKLSemicolonQuoteEnter
Shift LZXCVBNMCommaPeriodSlashShift R
Ctrl LMeta LAlt LSpaceAlt RMeta RCtrl R LUpDown R
Input check
Compare a suspect key with a working one
Focus the panel
Click inside the keyboard panel first. If focus moves elsewhere, click the panel again before testing.
Check press and release
Alternate between a working key and the suspect key. Compare the key, code, and state; holding a key also shows repeat events.
Try each mouse input
Test left, middle, and right buttons, then the wheel and pointer. Reset clears tested keys and the latest readings.
A worked example
Check the A key
- Start with
- Click panel → press A → release
- Check the result
- Look for KeyA and pressed/released states
The displayed character may change with input language or Shift, while the physical key code remains KeyA.