Keyboard Tester (Chatter & Rollover)
Pressed keys on a Korean 106, ANSI or ISO layout with rollover count, presses per key, chatter suspects in ms and hold time, plus keys browsers cannot see.
Privacy: keys, buttons and movement are counted inside this browser and not sent anywhere. Ads on this page (Google AdSense) work separately — see the privacy policy.
To log Wi-Fi or internet drops and Bluetooth connects and disconnects over time, use the Windows program PortDock Hardware Tester (free).
On-screen keyboards on phones and tablets do not report key positions (code), so this test does not fit them. Open it on a computer with a keyboard (a USB or Bluetooth keyboard on a tablet works).
While on, Space and arrows do not scroll the page and browser actions such as F5 or Tab do not fire. Chrome and Edge only: in full screen this page also receives Win, Alt+Tab and Esc. Hold Esc for 2 seconds to leave.
Dashed gray keys = keys the browser may not receive (not a fault). See «Keys the browser cannot see» below.
Input log (last 50)
| Time | Event | key | code | Interval / hold | Look at |
|---|
How to use
- Press keys one at a time and check that the same spot lights up. Keys pressed at least once stay tinted, and the small number is the press count.
- Rollover: hold several keys together and read «Max simultaneous». If a key does not light up in some combination, that is the keyboard's rollover limit (for example 6 keys) or anti-ghosting range.
- Chatter: if a single press shows two «down» rows marked as a chatter suspect, that switch is worth a look. Press the same key slowly several times to see if it repeats.
- Holding a key makes the OS send auto-repeat. Auto-repeat is not counted and never flagged as chatter.
How chatter is flagged
On the same key, if «previous press → this press» or «release → press again» is shorter than the threshold (30 ms by default), the press is marked as a chatter suspect. Human fingers usually take longer than that to release and press a key again. It is a hint, not a verdict — very fast tapping or OS and wireless receiver delays can play a part, so repeat the test a few times.
Keys the browser cannot see — not a fault
- Fn — Usually handled inside the keyboard, so nothing reaches the PC (Fn+F-key combos arrive as other keys such as brightness or volume). Neither browsers nor ordinary programs can see Fn on its own.
- Win (⊞) — Windows grabs it to open the Start menu, so the release or both events may never arrive. «Test in full screen» lets Chrome and Edge receive it.
- Print Screen — On Windows often only the release arrives. The log shows «up only» and it still counts as a press.
- Ctrl+Alt+Del, Win+L, Alt+Tab — The OS handles them first. Alt+Tab can be caught in «Test in full screen»; no web page can receive Ctrl+Alt+Del.
- Ctrl+W, Ctrl+T, Ctrl+N — The browser uses them for tabs and windows first (capturing cannot stop that).
- Korean Han/Eng, Hanja — The specification names them Lang1 and Lang2, but laptops and some keyboards send right Alt and right Ctrl instead, so those keys light up. The input method may also swallow them.
- Media and brightness keys — Depending on the keyboard they reach the browser (shown under «Keys outside the layout») or only the OS.
On equipment PCs too
It also helps on shop-floor and panel PCs where installing software is blocked, and with keyboard-wedge devices such as barcode scanners to see which keys they send and how fast (scanners type automatically, so they can trigger chatter suspects). For mouse button chatter, use the mouse double click test.
FAQ
One press types two characters
If the log shows two «down» rows for that key a few to a few tens of milliseconds apart, switch chatter is a likely suspect. Remove the keycap and clean it, or swap a hot-swap switch, and test again.
Some keys do not light up when I press several together
That is the keyboard's rollover limit or anti-ghosting range. Office keyboards often manage 2–3 keys in some combinations, and the basic USB mode allows six regular keys. This page counts exactly what the keyboard sends.
Are my keystrokes sent anywhere?
No. This tool's code makes no network requests, and keys are counted only inside this browser tab.