21 / Device Tests
Keyboard Tester & Anti-Ghosting Test
Test every key, spot possible chatter or stuck keys, measure rollover, and save a keyboard diagnostic report.
Last event
Waiting- event.code
- —
- event.key
- —
- Location
- —
- Count
- —
Recent keydowns
Event history
- No keys recorded yet.
Nothing is recorded until you start test mode.
Field note
Test a laptop, gaming keyboard, or external keyboard in one pass
Start test mode and press every key once. A teal key has registered; a red key is currently held. Switch to Compact when you only need the main typing block. The page reads physical event.code values, so it can distinguish left and right modifiers and the number pad.
Keyboard ghosting and N-key rollover test
Hold several keys together. Max rollover records the largest simultaneous group the browser received. A missing key in a combination may point to keyboard matrix ghosting, but operating systems and browser shortcuts can reserve some combinations.
How to check a stuck or double-typing key
The count beside each physical code keeps rising with every non-repeat press. A second press within 40 milliseconds is marked as possible chatter. Test the same key slowly at least 20 times before treating a flag as hardware trouble; fast intentional tapping can look similar.
Export a keyboard test report
Save / share creates a plain-text diagnostic file with tested keys, maximum rollover, chatter flags, and press counts. On iPhone or Android, the system share sheet can send the report to Files, Drive, Messages, or another app.