How to test your keyboard
- Press every key once. Working keys light up and stay marked with a green outline — the counter tracks your progress through all 104 standard keys.
- Type normally for a minute. If any key registers twice from one press, it's flagged as chatter automatically.
- Mash for rollover. Hold down as many keys as you can — the max rollover counter shows how many your keyboard can report at once.
- Copy the report if you need evidence for a warranty claim or a repair note.
Compact board? Keys your keyboard doesn't physically have (numpad on a TKL, F-row on a 60%) simply stay grey — that's expected.
Key chatter: why a key types twice
Inside every switch, metal contacts physically bounce when they close. Keyboards filter this with debounce logic, but as a switch wears or gets dirty the bounce gets longer than the filter — and one press becomes two. That's chatter. This tester flags any key that re-registers within 75 ms of being released, far faster than a human double-tap.
| Fix | Effort | When it helps |
|---|---|---|
| Compressed air into the switch while tapping it | 1 minute | Dust or debris in the switch |
| Raise debounce time in the keyboard's software (VIA/QMK or vendor app) | 5 minutes | Mild, occasional chatter |
| Contact cleaner (electronics-safe) into the switch stem | 10 minutes | Oxidised contacts |
| Swap the switch (hot-swap boards) or solder a new one | 30+ minutes | Worn-out switch |
Rollover and ghosting
Rollover is how many simultaneous keys your keyboard can report. Budget and laptop boards typically manage 6 plus modifiers (6KRO); most mechanical gaming boards support every key at once (NKRO). If you game with complex key combos — crouch + sprint + strafe + ability — low rollover is why some presses vanish. Hold down keys across different rows to test yours; the record sticks in the max rollover counter.
Dead key checklist
- Pull the keycap and clean underneath — crumbs are the #1 killer.
- Test the same key in another app or this tester after a reboot (a frozen app can eat keys).
- On hot-swap boards, reseat or replace the switch; check for a bent pin.
- If a whole row or column is dead, the issue is the PCB or controller, not the switches.
Frequently asked questions
How do I test if my keyboard keys work?
Press every key once — each working key lights up and stays marked as verified. Keys that never light up are dead or blocked; try cleaning under the keycap, then test again.
Why does my key type twice when I press it once?
That's key chatter (switch bounce). This tester flags any key that re-registers within 75 ms of release. Compressed air, contact cleaner, a higher debounce setting, or a switch swap are the standard fixes — see the table above.
What is key rollover (NKRO)?
How many keys register at the same time. Many budget boards handle 6 (6KRO); gaming keyboards often support full N-key rollover. Hold down as many keys as you can and watch the max rollover counter.
Why doesn't my Fn key show up?
Fn is handled inside the keyboard's own hardware and is never sent to the operating system, so no software can see it. If Fn combinations work (Fn+F5 changes brightness, say), your Fn key is fine.
Does this work with 60%, TKL and laptop keyboards?
Yes — any keyboard your computer recognises. Keys your layout doesn't have simply stay unverified on the diagram.
Are my keystrokes recorded or sent anywhere?
No. The test runs entirely in your browser — this site is static, with no server-side processing. Nothing you type is transmitted or stored.
More free tools
Testing a controller instead? Try the Gamepad Tester and Stick Drift Test · Everything else: all Alienated Tools.