Keyboard Tester: Check Every Key, Key Chatter and Rollover Online

How to use this keyboard tester

1. Click the keyboard area so it can capture keys. The border turns blue while it’s active.
2. Press every key once. Keys that register turn green; anything still white after you’ve pressed it didn’t reach the computer.
3. Check chatter: tap suspicious keys slowly, one at a time. A pink key means a second press arrived suspiciously soon after the first release.
4. Check rollover: hold down several keys together, for example your usual game keys (W, A, S, D plus Shift and Space). Watch the Held at once counter.
5. Stop: press Esc twice quickly, or click anywhere outside the area.

The layout shown is a full-size US (ANSI) keyboard. Laptop and compact keyboards simply don’t have some of the keys. Keys outside this layout, such as extra macro keys or other regional layouts, are listed under Extra keys detected in the summary.

What a key that doesn’t light up means

If you press a key and it stays white, the press never reached the browser. In rough order of likelihood:

• The operating system or keyboard handles it first. Fn, Windows/Command, Print Screen and media keys are often intercepted. Print Screen in particular often sends only a release, which the tool records with a note in the log.
• A remap is active: gaming keyboard software, PowerToys on Windows, or Karabiner on macOS can change what a key sends.
• Dirt or liquid under the keycap, common with laptop keys.
• A failed switch or a broken contact in the keyboard’s circuit. If several neighbouring keys fail together, a damaged trace or connector is more likely than individual switches.

Try the same key on another computer, or with another keyboard on this one. That quickly tells you whether the hardware or the software is at fault.

Key chatter: the double-typing problem

Chatter is when one press produces two or more characters, like “thhe” instead of “the”. It’s common on mechanical keyboards as switches age or collect dust. The tool measures the gap between releasing a key and the next press of the same key. If that gap is shorter than the threshold (40 ms by default), the key turns pink and the log shows an alert.

Tips:

• Test by tapping slowly. Fast, deliberate repeated taps can occasionally fall under the threshold. Alerts during slow tapping are the real signal.
• Holding a key down doesn’t count as chatter. The tool ignores the operating system’s auto-repeat.
• Fixes, from easiest:
  1. Remove the keycap and blow out dust.
  2. Raise the debounce time in your keyboard software, if it has that setting.
  3. On hot-swappable keyboards, swap the switch.
  4. On soldered boards, replace the switch or use the warranty.

Rollover and ghosting

Rollover is how many keys a keyboard can report at the same moment. Many basic keyboards guarantee only two or three keys in certain combinations. Gaming keyboards often advertise “N-key rollover” (every key at once). Ghosting is when a combination fails to register, or registers a key you didn’t press, because of how the keyboard’s wiring grid is laid out.

To test, hold the keys you actually use together and watch the Held at once number and the key colours. If one key in your combination refuses to light up while the others are held, you’ve found a limitation for that combination. Note that some keyboards in USB “boot” mode report at most six keys plus modifiers, and some laptops limit rollover for certain key groups.

Why the tester blocks shortcuts

While the area is active, it stops keys like Tab, Space, the arrow keys and F5 from scrolling or reloading the page, so you can test them freely. A few system shortcuts (for example Ctrl+W, Alt+Tab or the Windows key) are handled by the browser or operating system before any web page sees them. Those can’t be blocked and may still act.

Troubleshooting checklist

• Nothing happens when typing: click inside the keyboard area first. The border should turn blue.
• Wireless keyboard misses or repeats keys: replace or charge the battery and move the receiver closer. Weak signals cause both dropped and repeated keys.
• Only one app has the problem: if every key passes here, check that app’s shortcuts or input settings instead.
• Numpad does nothing: check Num Lock. With it off, the numpad keys act as navigation keys in other programs, but they still light up here because the tester reads the physical key.

Privacy

The tester only listens for key presses while you’re using it, and everything stays in your browser. Nothing you type is saved, logged to a server or sent anywhere.

Related tools

• Mouse Tester: check every button, double-click faults, scroll wheel and polling rate
• Microphone Test, Webcam Test and Dead Pixel Test: more free device tests

Fix it: Keyboard keys not working? How to find the cause and fix it

Last updated: October 5, 2026. Built and maintained by 123EasyTech.