Keyboard Chatter & Rollover Test
Tap each key a few times and this page watches the raw timing of every keydown event. A chattering switch registers two presses milliseconds apart from one physical tap — here it shows up as a red flagged event with the exact gap, so you can tell a failing switch apart from a software problem.
Not sure which device is at fault? Start with the input device fault diagnosis hub: it maps symptoms to the right test, then to repair, replace or return.
Start typing — tap each key five to ten times. Suspect keys should get extra taps.
Live board
Press physical keys to light them up — every keydown is timed and feeds the timeline below.
Recent keydown timeline
No keys pressed yet.
Rollover
0
max simultaneous keys this session — held keys stay lit on the board above, so hold four or five at once to see whether every switch registers (N-key rollover).
How the chatter test works
Every key press fires a keydown event with a precise timestamp from the browser. When a mechanical switch wears out, its metal contacts can bounce: one physical tap produces two or more keydown events 10–80 milliseconds apart. Operating systems also send repeated keydowns while you hold a key, but those carry a repeat flag, and this test explicitly excludes anything with that flag. Long-press repetition never pollutes the result.
The threshold choice matters. A 30ms gap is almost always genuine contact bounce. Anything above 80ms from a single tap is unusual for healthy hardware and points at a failing switch, a dusty stem, or a flaky USB connection. Run the test on the keys you actually use most; chatter tends to appear first on high-wear keys like space, E and the WASD cluster.
Chatter threshold guide
| Threshold | Use it for | What a flag means |
|---|---|---|
| 30 ms | Confirming a key that already flagged at 50 ms | Almost certainly genuine contact bounce — hardware fault confirmed |
| 50 ms (default) | First pass over every suspect key | Early switch wear; the key will start double-typing soon |
| 80 ms | Typing feels off but 50 ms shows nothing | Suspect the cable, receiver, or a dusty stem rather than the switch itself |
The ratio matters more than any single flag. One chatter event in twenty presses is borderline. More than one in twenty for the same key, reproduced across two runs, means the switch is failing. And a clean run at 50 ms with symptoms persisting points at software or the connection, not the switch.
Browser limits worth knowing
Letters, digits, modifiers, arrows, space and the numpad all feed the timeline above, and every key the browser can see is tested the same way. A few keys never reach the page at all: Windows key and macOS Cmd shortcuts are captured by the operating system, Fn and media/volume keys are handled at the firmware level, and PrtSc rarely fires a keydown. If those specific keys feel dead in daily use, test them outside the browser. Everything else on this board gets a full timing analysis here.
What to do if a key is flagged
Do not replace the keyboard. On hot-swap boards the fix is pulling one switch; on soldered boards it is a sub-dollar part plus an evening with an iron, and warranty covers chatter on most major brands. The keyboard chatter test guide covers the whole process, from threshold choice to the clean-versus-replace decision.
Frequently asked questions
My keyboard types double letters but no chatter shows up. What now?
Then the fault is likely software: check keyboard repeat settings, remove driver-level macro software, and test on another device. Hardware chatter shows up here as sub-threshold double keydowns from one tap.
What is N-key rollover?
It is the number of keys a keyboard can register simultaneously. Hold as many keys as you can; the counter shows the maximum. Most modern boards handle 6-key at minimum, gaming boards often advertise full N-key.
Why did the page stop counting when I switched tabs?
Browsers pause key events in background tabs and the timing baseline becomes unreliable. The test resets its timing baseline automatically when the page loses focus, so returning never produces false chatter.
Can I test a laptop keyboard?
Yes. The test reads standard browser key events, so any keyboard (laptop, external membrane, or mechanical) works the same way.
What is the difference between chatter and normal key repeat?
Key repeat is the OS deliberately sending the same letter while you hold a key down — it carries a repeat flag, and this test filters it out. Chatter is two or more keydown events from a single tap, produced by a bouncing switch contact. If this page flags a key, the hardware bounced; repeat never triggers a flag.
Does chatter testing work on membrane or scissor keyboards?
The test works, but chatter is far rarer on those types: membrane contacts switch cleanly and scissor mechanisms have little bounce. A membrane board that double-types is more likely a dirty contact or a failing controller, so the software checks (key repeat settings, macros, another device) matter even more there.
Why do the same few keys always fail?
Because wear is uneven. The keys you hit most — space, E, WASD on a gaming board — get the most switch actuations and fail first. A pattern that repeats on high-wear keys in the same position on the keyboard points to a switch, not to a USB or driver problem, which would usually affect the whole board at once.
What does my rollover number actually mean for gaming?
Rollover is how many keys register simultaneously. 2–3 means simple matrix boards that drop keys during complex combos; 6KRO covers most games comfortably; full N-key means no practical limit. The counter shows the maximum you held at once, so play the combo you actually use — if it never drops, your board is not the bottleneck.