Keyboard Tester

This tool listens for KeyboardEvent signals from your browser — keydown and keyup — and maps every event to a physical key on the standard layout. Nothing is installed, nothing is sent to a server. The entire test runs in your browser tab.

Step 1: Press Any Key

Each key you press lights up on the visual layout. Keys stay highlighted after release so you can track which keys you've already tested. Press every key once to confirm all switches are registering.

Step 2: Check for Dead Keys

After pressing all keys, any key that remains unhighlighted may have a faulty switch, a broken solder joint, or a firmware issue. On mechanical keyboards this usually means the switch needs replacement; on membrane keyboards the contact pad may be worn.

Step 3: Test N-Key Rollover

Press as many keys as you can at the same time. The counter shows simultaneous key registrations. True NKRO keyboards via USB register every key independently — you should see 10+ simultaneous keys without drops. 6-key rollover (6KRO) keyboards stop registering after 6 simultaneous keys. Most Bluetooth keyboards are limited to 6KRO due to protocol constraints.

Step 4: Test for Ghosting

Ghosting occurs when pressing certain key combinations causes phantom key registrations — keys you didn't press appear highlighted. This is a hardware limitation of the keyboard's matrix wiring. Anti-ghosting keyboards add diodes to each switch to prevent this. Try pressing 3-key combinations like Q+W+E or A+S+D to test.

Step 5: Check Key Chatter

Press and release a single key slowly, once. If the counter registers 2+ presses from one physical press, the switch is chattering — sending multiple signals per actuation. This is common in aging mechanical switches and can sometimes be fixed with contact cleaner or firmware debounce settings.

Mechanical Keyboards

All mechanical switch types are fully supported — Cherry MX (Red, Blue, Brown, Black, Speed, Silent), Gateron, Kailh (Box, Speed, Choc low-profile), Holy Panda, Topre (electrostatic capacitive), and optical switches (Razer, Gateron Optical). Hot-swap keyboards work identically to soldered ones. The tester detects key events regardless of switch type.

Membrane & Rubber Dome

Standard office keyboards, laptop keyboards, and budget gaming keyboards with membrane switches are fully supported. These typically have 6KRO and may exhibit ghosting on certain key combinations. The tester helps you discover these limitations.

Laptop Keyboards

Built-in laptop keyboards (scissor switch, butterfly switch) work normally. The Fn key is handled at the hardware/firmware level and may not generate a browser event. Function key combos (Fn+F5 for brightness, etc.) send the secondary function's keycode. Media keys are detected when they generate standard key events.

Wireless & Bluetooth

Bluetooth and 2.4 GHz wireless keyboards are supported. Note that Bluetooth keyboards typically operate at 6KRO due to the Bluetooth HID protocol limitation. USB dongle wireless keyboards (2.4 GHz) can support full NKRO depending on the receiver implementation.

Layouts

The visual display shows a standard ANSI (US) layout as reference. The tester detects physical key positions via key codes, so it works with any layout — QWERTY, AZERTY (French), QWERTZ (German), Dvorak, Colemak, JIS (Japanese), ISO (European). Your physical key position is what matters, not the character it produces.

Key Not Registering

• Single key dead: Likely a faulty switch (mechanical) or worn contact pad (membrane). On hot-swap boards, try reseating or replacing the switch.
• Entire row/column dead: Indicates a matrix connection issue — possibly a broken trace on the PCB or a loose ribbon cable (laptops).
• Fn key not detected: Normal. Most Fn keys are intercepted by the keyboard firmware and never reach the browser.

Multiple Keys Register From One Press (Chatter)

• Adjust debounce time in your keyboard's firmware (QMK/VIA keyboards: increase debounce to 10-15 ms).
• Clean the switch with compressed air or electronic contact cleaner sprayed into the switch housing.
• Replace the switch on hot-swap boards — chatter is often a sign of worn contact leaves.

Key Combination Ghosting

• Ghosting is a hardware limitation and cannot be fixed with software.
• Keyboards marketed as "anti-ghosting" have diodes per switch that prevent phantom key events.
• If specific gaming combinations ghost (e.g., W+A+Space), consider a keyboard with full NKRO.

Wireless Keyboard Latency

• Bluetooth: Typical latency is 7-15 ms. Ensure the keyboard isn't in power-saving mode (wake it by pressing a key first).
• 2.4 GHz dongle: Typically 1-4 ms — close to wired performance. Keep the dongle close to the keyboard.
• USB wired: 1 ms polling at 1000 Hz. Always the lowest latency option.