Device Checks
Keyboard Tester — Check Keys, Ghosting, and Rollover
Press every key to verify it registers. Test N-key rollover, spot ghosting, and identify dead switches.
Tested
0 / 104
Currently held
0
Max rollover
0
Heads up: this tool needs a physical keyboard. Open it on a desktop or laptop for the real experience — you can still scroll the FAQ below.
Currently pressed
—
Click on the keyboard area first if presses aren't registering
2KRO vs 6KRO vs NKRO
2-key rollover (2KRO) — basic membrane keyboards. Detects up to 2 keys at once. Fine for typing, fails in many gaming combos.
6-key rollover (6KRO) — standard for wired keyboards. Detects 6 simultaneous non-modifier keys plus the 4 modifier keys. The USB HID spec ceiling for the basic protocol.
N-key rollover (NKRO) — every key registers, no matter how many you press. Required for serious gaming, music software, and competitive typing.
Frequently asked questions
What is N-key rollover?
N-key rollover (NKRO) means your keyboard can detect every key pressed simultaneously, no matter how many. Most keyboards have 2-key or 6-key rollover — they can detect up to 2 or 6 keys at once. NKRO is important for fast typing, gaming (especially games requiring multiple movement + action keys), and music software that tracks multiple held notes.
Why can't the test detect my Fn key?
Fn is handled at the keyboard's firmware level, not by the operating system. The Fn key remaps other keys (like media controls on F-keys), but it never sends its own signal to your computer. No browser-based test can detect it. Your Fn key is working if the remapped functions (volume, brightness) work.
Is keyboard ghosting fixable?
Ghosting happens when your keyboard can't register certain 3-key combinations because of how its circuit board is wired. It's a hardware limitation — it cannot be fixed in software. The only fix is a keyboard with better key matrix design (anti-ghosting) or NKRO. Most mid-range and above mechanical keyboards are advertised as anti-ghosting or NKRO.
How do I check if my keyboard is faulty?
Use the 'Press All Keys' tab above — press every single key in sequence and look for any that don't turn green. If a key doesn't register, try: cleaning under the keycap with compressed air, testing in a different USB port, or trying a different cable if detachable. If those don't help, the switch is likely dead.
What does NKRO do?
NKRO lets your keyboard transmit any number of simultaneous keypresses without dropping any. This matters for speed typists who hit multiple keys close together, gamers pressing movement + strafe + ability at once, music keyboards tracking chords, and pianists playing multi-finger passages on software pianos. For regular typing and office work, 2KRO is usually enough.
Should I enable NKRO?
If your keyboard has an NKRO toggle (usually Fn + some key), enable it only if you actually need it — gaming, music, or speed typing. Some older operating systems don't play well with full NKRO over USB, which is why the toggle exists. If you notice keys dropping during normal use, enable NKRO; otherwise, 6KRO is fine.
Why does my keyboard feel different on laptop vs external?
Most laptop keyboards use rubber dome or scissor switches with very short travel (1–2 mm), while external mechanical keyboards use individual switches with 3.5–4 mm travel and a distinct actuation point. This affects typing feel, speed, and accuracy. Neither is better — they're optimized for different use cases.
Related