Online Keyboard Tester
Check every key on your keyboard works: a full visual map that lights up on press, an anti-ghosting test with simultaneous presses (how many your keyboard registers at once), a total counter and last-key readout. Perfect for dead keys or brand-new keyboards.
Total keys
0
Max simultaneous (NKR)
0
Last key
—
Hold several keys at once to measure anti-ghosting: the maximum number of simultaneous presses your keyboard registers without dropping any. Typical mechanical boards register 6-10 or more (N-Key Rollover); membrane ones sometimes stop at 2-3.
Built by
Miguel Ángel Colorado Marin (MACM)
Built by
Miguel Ángel Colorado Marin (MACM)
Full-Stack Developer · Guadalajara, España
I develop web apps, digital tools and full projects — from design to deployment.
One unresponsive key ruins a work session or a game, and hunting it by hand is painful. This tester draws your full keyboard — 106 physical keys with the W3C standard codes (KeyboardEvent.code) — lighting up as you press. The key test is anti-ghosting: hold several keys at once and the «max simultaneous» counter shows how many your keyboard registers without dropping any — N-Key Rollover boards pass 6, membrane ones usually stop at 2-3. It works on physical codes, not characters, so dead keys are detected even with OS shortcuts in the way; legends switch between Spanish (Ñ, Alt Gr, ¡¿) and English. Counters reset with one click, and keys held when you switch tabs release themselves.
Features
- ✓Full 106-key visual map: alphanumerics, function row, navigation, arrows and numpad
- ✓Instant key highlight using the physical code (KeyboardEvent.code)
- ✓Anti-ghosting test: hold several keys and see how many register at once
- ✓Spanish (Ñ, Alt Gr) and English legends, switchable
- ✓Dead-key detection: a key that never lights up has a bad switch or diode
How to test keyboard keys?
- 1
Press every key
Sweep the map top to bottom: each key lights up the instant the browser registers the press.
- 2
Measure anti-ghosting
Hold 2 keys, then 3, 4, 5…: the «max simultaneous» counter keeps your keyboard's best.
- 3
Hunt dead keys
A key that never lights up has a bad switch or diode; on laptop keyboards it's usually the ribbon cable.
- 4
Check combinations
Test the combos you actually use: Ctrl+Shift+X, Alt Gr+E, Win+D — all three light up together.
Frequently asked questions
What is anti-ghosting and why does it matter?
When you press several keys at once, the keyboard scans a row-column matrix: without enough diodes you get ghosting (phantom characters) or dropped presses. The test measures how many simultaneous keys your board registers — N-Key Rollover (6+) is standard on mechanical boards and what gamers or fast typists need.
Why doesn't my X key light up?
If the physical key never lights up, the fault is in the keyboard itself (switch, diode or laptop ribbon cable). The tester uses the physical code, so if the press doesn't reach the browser it isn't reaching the OS either.
Are my keystrokes recorded?
No. Detection happens in memory while the page is open and only feeds the visual map: no text capture, no uploads, nothing persists after closing the tab. The counter is a number, not a keylog.
Embed Keyboard Tester on your site
Add Keyboard Tester to any web page with a simple iframe. Free, with attribution to miguelacm.es.
<iframe
src="https://miguelacm.es/embed/keyboard-tester"
width="100%"
height="700"
frameborder="0"
title="Keyboard Tester — miguelacm.es"
></iframe>