Keyboard Tester
Test every key on your keyboard online with an interactive visual keyboard map. Check for stuck switches, key ghosting, key codes, and N-key rollover. Free, no download.
A keyboard tester is an interactive tool that highlights every pressed key on a visual layout to verify switch actuation. It checks whether dead keys, stuck switches, key ghosting, or matrix jamming are occurring, and verifies N-key rollover (NKRO) during simultaneous multi-key combinations.
Full Virtual Keyboard Tester
What Is a Keyboard Key Tester?
A keyboard tester provides a real-time virtual layout of standard ANSI and ISO keyboards. When you press a physical key, the browser intercepts the standard KeyboardEvent, decodes its physical e.code and typographical e.key value, and lights up the corresponding switch on screen.
This diagnostic is essential for troubleshooting spilled liquids, dust in mechanical switches, soldering defects on custom keyboards, worn rubber membranes on laptops, and matrix jamming on entry-level office keyboards.
It also evaluates N-Key Rollover (NKRO)—the hardware ability to register an unlimited number of simultaneous keystrokes without dropped inputs or phantom ghost keys.
How to Test Your Keyboard
Click anywhere on the virtual keyboard to ensure the browser has active keyboard focus.
Tap through every row: Function keys (F1-F12), number row, QWERTY alphanumeric keys, modifiers (Shift, Ctrl, Alt), and navigation arrows.
Active keys illuminate while held down and turn into a persistent confirmed state once released, allowing you to systematically verify the entire layout.
Press and hold multiple keys simultaneously (e.g., W + A + S + D + Space + Shift) to confirm your keyboard controller can process concurrent gaming combinations.
Review the live telemetry panel showing event.code, event.key, event.which, and OS repeat state for developer diagnostics.
How to Read Your Results & Performance Benchmarks
Compare your observed diagnostic measurements against verified hardware standards.
| Rollover Class | Simultaneous Keys | Matrix Architecture | Gaming Suitability |
|---|---|---|---|
| 2-Key Rollover (2KRO) | 2 keys max | Cheap un-dioded membrane | Ghosting common; fails during diagonal sprint + jump. |
| 6-Key Rollover (6KRO) | 6 keys + modifiers | Standard USB HID legacy limit | Sufficient for 95% of gaming; standard USB office board. |
| N-Key Rollover (NKRO) | Unlimited concurrent | Individual diode per switch | Full esports grade; zero ghosting or jamming possible. |
Common Keyboard Faults and How to Fix Them
Cause: Oxidized mechanical switch contacts, accumulated dust/crumbs, or worn rubber membrane carbon pads.
Cause: Sticky mechanical switch stem, broken return spring, or OS Sticky Keys feature enabled.
Cause: Hardware-level Fn keys modify scan codes inside the keyboard microcontroller without sending standard OS key events.
The browser KeyboardEvent API captures all standard standard keyboard inputs. However, certain system hotkeys (like Ctrl+Alt+Del, Windows Key, or browser shortcut keys like Ctrl+W and F5) are intercepted directly by the operating system or browser chrome before reaching JavaScript.
Frequently Asked Questions
How do I test if a key is broken?
What is key ghosting?
What is N-Key Rollover (NKRO)?
Why do some keys like F5 or Alt+Tab act strangely in the test?
Does this keyboard test work on Mac keyboards?
Related Hardware & Input Diagnostics
Cross-verify your peripherals with our full suite of local, private browser tests.
Mouse Polling Rate Test
Measure real-time mouse update frequency (Hz), peak rate, interval jitter, stability, and latency distribution directly in your browser.
Keyboard Polling Rate Test
Evaluate key event intervals and browser-observed matrix update frequency during rapid keystrokes.
Spacebar Speed Test
Measure spacebar mash rate, presses per second, and thumb stamina across 5s, 10s, and 30s sessions.
Key Press & Latency Test
Analyze keydown to keyup press durations, OS repeat delay, repeat frequency, and modifier combinations.