Keyboard Test
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A dead or unreliable key is easy to miss until you actually need it, and 'how many keys can I hold at once' is close to impossible to judge by feel. This free tool lights up an on-screen keyboard diagram as you press, marks every key you've confirmed, and counts how many you're holding at once — sweep the whole board to find your keyboard's actual rollover ceiling in a couple of minutes.
How it works
- Click or Tap the Diagram to Focus It. The diagram only registers key presses once it's focused.
- Check the Layout Matches Your Keyboard. Switch the diagram between ANSI and ISO to match your keyboard's actual shape.
- Press Every Key You Want to Check. Press each key row by row — it lights up the instant it registers.
- Watch It Dim to a 'Tested' Mark on Release. Released keys stay marked instead of resetting, so you can see at a glance what's left to test.
- Hold Several Keys at Once to Check Rollover. Hold a real combo, like W+A plus Shift plus Space, and watch the live counter to find your rollover ceiling.
- Reset to Sweep Again. Reset clears every tested mark without affecting a key you're still holding down.
How to Read the Diagram
Every key has three states: neutral (not pressed yet), bright (held down now), and marked (pressed and released). The goal is to turn every key into a marked one, so a glance shows what's left to check.
What Key Rollover (and Ghosting) Actually Means
Every keyboard has a limit on how many keys it can correctly report at the exact same time. That limit is called its rollover, and it's usually described as N-key rollover, or NKRO, when a keyboard can report every key on the board simultaneously with no limit at all.
- 2-key rollover: only 2 keys register reliably at once; common on very basic keyboards.
- 6-key rollover (6KRO): up to 6 non-modifier keys plus modifiers at once. This is the USB standard 'boot protocol' limit, and it's the ceiling on a large share of ordinary keyboards.
- N-key rollover (NKRO): every key can be held at once with no practical limit, using a USB report format built for it rather than the 6-key boot protocol.
Ghosting is a related but different problem. On a keyboard matrix without a diode at every key, certain 3-key combinations can make the controller register a key you never pressed, or drop one you did. Some keyboards avoid this by refusing extra input once a risky combination is detected, rather than reporting a wrong key. Either way, it shows up here as a key that won't light up alongside certain others.
Why Rollover Differs Between Keyboards
Rollover isn't about mechanical vs. membrane vs. optical switches directly, it's about whether the keyboard has a diode at every key and whether its firmware reports over USB using the full-NKRO format or the simpler 6-key boot format.
- Membrane and cheap laptop keyboards often skip per-key diodes to cut cost, capping rollover around 2 to 6 keys.
- Gaming mechanical keyboards often wire a diode into every switch and report full NKRO, making rollover genuinely limitless.
- Optical and Hall-effect switches don't cause rollover themselves, but they're often bundled with full NKRO wiring, linking them to high rollover in practice.
- Some keyboards need a driver, key combo, or software toggle to switch from 6KRO to full NKRO mode — check your manual if this test reports a lower ceiling than advertised.
ANSI vs. ISO: Which One Is My Keyboard?
These are the two common physical shapes for a Western keyboard layout, and they're a hardware-shape question, not a language one.
- ANSI (US shape): a single flat, wide Enter key, and no extra key between left Shift and Z.
- ISO (used across most of Europe, including Romania): a taller, narrower Enter key that hangs down into the row below, plus one extra key immediately to the right of left Shift.
Picking the 'wrong' one only changes which shape is drawn — every key still tests correctly either way.
Why Didn't a Key Light Up? Troubleshooting
Before assuming a key is faulty, rule out the keys that were never going to reach this page in the first place.
- Ctrl+Alt+Delete on Windows is intercepted at the OS level for security; no application, including a browser, can see it.
- Fn on most laptops isn't a normal key — the keyboard's firmware usually remaps it before it becomes a USB signal, so it rarely reaches any web page.
- Many browser and OS shortcuts are reserved regardless of the page — tab switching, Mission Control, screenshot keys; not lighting up there is expected, not a fault.
- Media, volume, and brightness keys are often handled entirely by the OS and never generate a key event a webpage can read.
If a normal letter, number, or modifier key still never lights up after ruling those out, that's worth investigating: check for debris, a low battery or dropped wireless connection, or a background remapping tool.
Per-OS and Browser Notes
A handful of details are worth knowing before you test.
- OS- and browser-reserved shortcuts always win, regardless of browser (see Troubleshooting above).
- On-screen touch keyboards don't produce real physical key codes, so this test needs a physical keyboard, wired or wireless.
- This test reads physical key position, independent of your OS's input language, so it works in any language setting.
Frequently asked questions
Does this record or log what I type?
No — everything runs locally in your browser, purely to light up keys on screen; nothing is recorded, logged, or sent anywhere.
Why didn't a key light up?
See Troubleshooting above — most non-responsive keys are reserved OS or browser shortcuts, not faults. If a normal key still won't light up, it may genuinely be faulty.
Is a low rollover count normal, or is my keyboard broken?
Normal, in most cases. Rollover depends on whether a keyboard has a diode at every key and how its firmware reports over USB — plenty of ordinary membrane and laptop keyboards cap out around 2 to 6 keys by design. That's rarely noticeable for typing, which seldom holds more than two or three keys down at once.
What's the difference between rollover and ghosting?
Rollover is how many keys a keyboard can report at once. Ghosting is a wiring-related failure where certain key combinations register a wrong key or drop one you pressed.
Why does the on-screen diagram look different from my physical keyboard?
You're likely viewing the other layout — ANSI or ISO (see the section above). Toggle the layout switch above the diagram to match your hardware; every key still tests correctly either way.
Does this work with a Bluetooth or wireless keyboard?
Yes — as long as it's connected and typing normally, a wireless keyboard behaves the same as a wired one. If keys feel inconsistent, check battery level and connection before assuming a hardware fault.
Does my keyboard's language or input layout affect the test?
No. The test reads each key's physical position, not the character it types, so any input language works.
Can I test a laptop's built-in keyboard the same way as an external one?
Yes, both work the same way here. Laptop keyboards often land on the lower end of the rollover range than dedicated mechanical keyboards, which is normal for that hardware class, not a sign of a problem.
How many simultaneous keys should a normal keyboard support?
There's no single right answer, it depends on the keyboard class. Budget membrane and many laptop keyboards commonly land around 2 to 6 keys, while gaming mechanical keyboards often advertise full N-key rollover with no practical limit. Either is entirely normal for what it's designed for.
Every part of this test runs locally in your browser; no keystrokes, key combinations, or anything else about what you type are ever recorded, logged, uploaded, or stored anywhere.