How to Test Keyboard Keys for Dead Keys & Ghosting

Guides · Web · Updated 2026

Whether you’re buying a used laptop or your “A” key suddenly stops working, a quick keyboard test can save you hours of frustration. With a free online tool you can press every key and see exactly which ones register — and which don’t. This guide walks you through the process and explains common keyboard issues like ghosting.

Why you should test a keyboard before buying

Used laptops and mechanical keyboards can have hidden problems. A key may feel fine but fail to send the correct signal, or a liquid spill may have damaged internal contacts. An online keyboard tester gives you immediate visual feedback, highlighting each pressed key on an on‑screen layout, so you can spot any that are dead, repeating, or sending the wrong code.

Step-by-step: test your keyboard

Open the Keyboard Tester tool on the device with the keyboard you want to test.
Click inside the page to give it focus, then start pressing keys. Each key you press will light up on the on‑screen QWERTY layout and stay highlighted — perfect for identifying which keys you’ve already tested.
For each press, note the Key, Code, and KeyCode values displayed below the keyboard. If a key shows an unexpected character, it might be set to the wrong language layout.
Press every key, including modifier keys like Shift, Ctrl, Alt, and the spacebar. The tool prevents the page from scrolling when you press Space or the arrow keys, so the test runs smoothly.
Once all keys have been pressed at least once, click Reset to clear highlights and re‑test any suspect keys.

💡 Tip: If you’re testing a brand‑new mechanical keyboard, try pressing multiple keys at once (e.g., W + A + Shift) to check for “ghosting” — where some key combinations don’t register. The tool shows exactly which keys are currently active.

What to do if a key is dead or sticky

If a specific key doesn’t light up on the tester, try cleaning under the keycap with compressed air. On a laptop, a dead key may indicate a damaged internal ribbon cable — often not worth repairing on cheaper models. Sticky keys that register multiple times with one press could be a sign of dirt or a faulty switch; a thorough cleaning often fixes them.

Frequently Asked Questions

Can I test an external USB keyboard with this tool?

Yes. Simply plug it into any computer, open the tool in a browser, and the tester will detect input from whichever keyboard you’re using.

What is ghosting, and how does the tester help?

Ghosting happens when certain key combinations cause extra phantom key presses. Our tester highlights all active keys in real time; if you press three keys and a fourth lights up, you’ve confirmed ghosting.

Does the test work with non‑QWERTY layouts (AZERTY, QWERTZ)?

The on‑screen keyboard is fixed to a QWERTY layout, but the key‑info display still shows the correct Key and Code values for any keyboard layout your system is set to. The highlights may not match the printed key caps exactly, but the core function works.

Can I test my phone’s on‑screen keyboard?

No — the tool relies on physical key press events. On‑screen mobile keyboards use touch events, so the tester won’t register them.

Is it free and private?

Yes — the tool runs entirely in your browser, free, with no sign‑up and nothing uploaded to a server.

Try the Keyboard Tester