Keyboard Tester
A keyboard tester detects which keys on your keyboard are registering correctly in real time — showing you instantly whether any key is broken, stuck, or ghosting. Press any key and it lights up on the on-screen layout, confirming the signal reached your computer. This matters more than most people realise: studies of gaming keyboards show that over 40% of budget membrane keyboards start dropping keypresses when you hold more than 3 keys simultaneously — a problem called keyboard ghosting — which directly hurts performance in fast-paced games where W + A + Shift + Space must all register at once.
The other thing this tester measures is your keyboard's N-key rollover (NKRO) — the maximum number of keys it can register at the same time. Budget keyboards typically cap at 2KRO or 6KRO; quality mechanical keyboards offer full NKRO (unlimited simultaneous keys). You can test this yourself: hold down as many keys as you can and watch the “Keys Held Now” counter — the higher the number before inputs stop registering, the better your keyboard.
The tester works on any USB, Bluetooth, or wireless keyboard on Windows, macOS, and Linux — no download, no install, no account. Just click the tool below and start typing. Common use cases include verifying a newly bought keyboard before the return window closes, diagnosing why certain key combos fail in games, checking a laptop keyboard for dead or stuck keys, and testing a mechanical keyboard after cleaning or lubing the switches.
Choose Your Keyboard Type
Each variant has tailored tips, rollover benchmarks, and FAQs specific to that keyboard type.
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Keys Held
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Max Simultaneous
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Keys Tested
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Press any key to test it. Blue = held, Green = tested.
How to Test Your Keyboard
Press Each Key
Tap every key individually. Blue = currently held, Green = tested and released. Any key that stays dark after pressing may be broken or stuck.
Test Rollover
Hold W + A + Shift + Space simultaneously. The 'Keys Held Now' counter shows how many keys are registered at once — the higher, the better for gaming.
Check Your Score
The progress bar tracks what percentage of all keys you've tested. Aim for 100% to confirm every key works before a gaming session or purchase return.
What Is a Good N-Key Rollover Score for Gaming?
Rollover determines how many simultaneous keypresses your keyboard can register without dropping inputs. Most gaming actions use 3–5 keys at once (WASD + Shift + Space). The table below shows what each rollover level means in practice.
| Rollover | Keys at Once | Typical Keyboard | Gaming Verdict |
|---|---|---|---|
| 2KRO | 2 | Budget membrane | ❌ Not suitable |
| 6KRO | 6 | Most gaming keyboards | ✅ Sufficient for most games |
| NKRO (USB) | 14–18 | Mid-range mechanical | ✅ Excellent |
| NKRO (PS/2) | Unlimited | High-end mechanical | ✅ Best possible |
Keyboard Ghosting by Switch Type
Keyboard ghosting — where a keypress is dropped because too many keys are held simultaneously — varies significantly by keyboard technology. Membrane keyboards are the most affected; mechanical keyboards with NKRO are immune. Use this table to understand your keyboard type.
| Keyboard Type | Ghosting Risk |
|---|---|
| Budget membrane | High |
| Mid-range membrane | Medium |
| Mechanical (6KRO) | Low |
| Mechanical (NKRO via USB) | None |
| Mechanical (NKRO via PS/2) | None |
| Laptop keyboard | Medium |
| Optical / Hall-effect | None |
Ghosting is a hardware limitation — it cannot be fixed with software. To test your keyboard, hold WASD + Shift + Space and watch the Keys Held counter above.
Why Is My Keyboard Not Working? 5 Fixes to Try First
Before replacing a keyboard or visiting a technician, run through these fixes in order. Most keyboard issues are caused by software, dirt, or a wrong port — not actual hardware failure. The tester above will tell you whether you have a hardware problem or a ghosting/driver issue.
Restart or reconnect the keyboard
Unplug a wired keyboard and plug it back in, or for wireless, turn it off and on again and re-pair the dongle. Many "broken" keys are caused by a lost USB handshake that clears on reconnect. If restarting the keyboard doesn't help, restart the computer — the OS occasionally drops keyboard interrupt handlers.
Try a different USB port
USB hubs and front-panel ports deliver less power than rear motherboard ports. Plug your keyboard directly into a rear USB-A port and test again. If keys start working, the original port is underpowering the keyboard — a common issue with high-end mechanical keyboards that have RGB lighting.
Clean the stuck key
A key that shows as pressed in the tester without you touching it is physically stuck. Turn the keyboard upside-down and tap lightly to dislodge debris. For mechanical keyboards, use a keycap puller and compressed air on the switch housing. For membrane keyboards, slide a thin card under the key edge to free it. Do not use water — use 90%+ isopropyl alcohol on a cotton swab if the key is sticky.
Update or reinstall the keyboard driver
On Windows, open Device Manager → expand Keyboards → right-click your keyboard → Update Driver. If keys are missing completely (not just ghosting), right-click → Uninstall Device, unplug the keyboard, replug — Windows will reinstall the generic HID driver automatically. On macOS, go to System Settings → Keyboard → Keyboard Shortcuts → Modifier Keys and confirm the layout is set correctly.
Check if it's ghosting, not a broken key
Use the tester above: if a key works when pressed alone but disappears when you hold 3–5 other keys, the problem is ghosting — a hardware limitation of the keyboard matrix, not a broken key. Ghosting cannot be fixed with a driver update. The only solution is a keyboard with higher rollover (6KRO or NKRO). See the ghosting table above for which keyboard types are affected.
Frequently Asked Questions
How do I use the keyboard tester?
Simply press any key on your physical keyboard. The corresponding key on the on-screen layout will light up blue while held and turn green once released, confirming it was detected. No clicks or setup required — just start typing.
What is N-key rollover (NKRO)?
N-key rollover means the keyboard can register an unlimited number of keys pressed simultaneously without any being dropped or missed. The 'N' stands for any number. Gaming keyboards often advertise 6KRO (6-key rollover) or full NKRO. To test yours, hold down as many keys as possible and watch the 'Keys Held Now' counter — if it stops increasing before all your keys are held, you've found the rollover limit.
What is keyboard ghosting?
Keyboard ghosting is when a keypress is not registered because too many other keys are held at the same time, or because certain key combinations interfere with each other. It happens due to the electrical matrix design of budget keyboards. NKRO keyboards eliminate ghosting by using a separate circuit per key. You can test for ghosting using our tester by holding common gaming key combos like W + A + Shift + Space.
How do I test for stuck or broken keys?
Press every key individually across the full keyboard layout. Any key that does not light up green after being pressed is either stuck (registered as always-pressed before you even touch it) or broken (not registering at all). The 'Keys Tested' counter tracks your progress so you can ensure every single key has been verified.
Why is my keyboard not detected by the tester?
The tester listens for key events in your browser. Some keys are captured at the OS level and never reach the browser — these include PrintScreen, some media keys, and function keys that trigger OS shortcuts. Make sure the page is in focus (click on it once) before testing. If a key still doesn't register, it may be a hardware fault.
Does the keyboard tester work with gaming keyboards?
Yes. The tester works with any keyboard your OS can read — mechanical, membrane, gaming, laptop, or Bluetooth. It reads raw key codes directly, so even custom layouts and gaming keypads will work as long as your OS recognises the keypress.
Can I test a wireless or Bluetooth keyboard?
Yes. Wireless and Bluetooth keyboards work exactly the same as wired keyboards in this tester — the browser only sees key events, not the connection type. The only difference is that wireless keyboards may have slightly higher latency (typically 1–10ms extra), which you won't notice in day-to-day use but can matter in competitive gaming. Connect via USB dongle rather than Bluetooth for the lowest wireless latency.
Does the keyboard tester work on Mac?
Yes, the tester works on macOS in any modern browser (Chrome, Safari, Firefox, Edge). A few Mac-specific caveats: the Command key may not register because macOS captures it at the system level before the browser sees it. Some function keys (F3, F4, Mission Control, etc.) are intercepted by macOS too. For best coverage on Mac, click the page once to focus it and test in Chrome, which has the widest key event support.
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