Keyboard Tester

Confirm every key works, catch stuck keys and ghosting, and inspect key codes and rollover in real time.

Keyboard Tester

Keyboard Visualization

Idle
Tested 0 keys

Click here and press any key to begin.

A physical keyboard is required. Each key you press turns green so you can confirm every key registers.

Key Details

Last Keyn/a event.keyn/a event.coden/a keyCoden/a Locationn/a Auto-Repeatno

Modifiers

Shift Ctrl Alt Meta

Locks

Caps Num Scroll

Runtime Diagnostics

Keyboard APIchecking… Currently Held0 Max Simultaneous (rollover)0 Unique Keys Tested0 Total Key Presses0 Stuck-Key Warnings0 Keyboard Tester Version1.0.2

Event Log

Event Key Code Time
No key events recorded yet.

All processing happens locally in your browser. No keystrokes are sent to any server.

What This Tool Does

Keyboard Tester validates keyboard input directly in-browser using a full-size ANSI 104-key visualizer. Every key you press lights up and stays marked as tested, so you can confirm the whole board registers. It is useful for QA verification, hardware checks, refurbishing, and everyday troubleshooting of a keyboard that feels dead, sticky, or unreliable.

This tool helps you verify:

  • That every key registers a press (persistent tested-key highlighting)
  • Key details: key, code, keyCode, location, and auto-repeat
  • Modifier state (Shift, Ctrl, Alt, Cmd/Win) and locks (Caps, Num, Scroll)
  • Maximum simultaneous keys registered (key rollover / anti-ghosting)
  • Stuck keys, flagged automatically when a key is held too long
  • Exportable event logs and a JSON diagnostics report for support evidence

How to Use

  1. Click inside the keyboard test area to start listening.
  2. Press each key once and confirm the matching key turns green.
  3. Watch the Key Details panel to see the key value, physical code, and location.
  4. Hold several keys at once to check Max Simultaneous (rollover).
  5. Press Shift, Ctrl, Alt, Cmd/Win and toggle Caps/Num/Scroll to confirm the badges light.
  6. Look for any key flagged red, which indicates a possible stuck key.
  7. Use Reset Tested to clear highlights and counters and start a fresh pass.
  8. Use Export Log or Download JSON Report when you need diagnostics evidence.

Understanding Results

  • Pass: Every key you press highlights green and appears in the log.
  • Dead / unresponsive key: A key never turns green no matter how you press it, pointing to hardware or contact failure.
  • Stuck key: A key stays highlighted or is flagged red without being held, indicating a mechanical or contact fault.
  • Limited rollover: Only a few keys register at once. On non-NKRO keyboards this is normal, not a fault.
  • Missing key event: The browser or operating system intercepted the key first (common with some media keys and OS-level shortcuts).

Frequently Asked Questions

Do I need to install software to run this test?

No. The diagnostics run in-browser through the standard Keyboard event API.

Can I use this with an on-screen or mobile keyboard?

A physical keyboard is required. On-screen keyboards on phones and tablets do not emit standard key events.

What is key rollover / ghosting?

Rollover is how many keys your keyboard can register at the same time. When the limit is reached, extra presses are dropped (“ghosting”). The Max Simultaneous readout shows the highest count reached.

Why did a browser shortcut fire instead of registering the key?

The tester suppresses most default actions (Tab, Space, arrows, F-keys) while focused, but some OS-level shortcuts such as Ctrl+W or Cmd+Q cannot be intercepted by a web page.

I’m on a Mac. Which keys are shown?

The modifier keys display as Cmd and Opt on macOS, and as Win and Alt on Windows.

Troubleshooting

A key does not register

  • Press firmly and confirm the test area is focused (click it first).
  • Try the key in another application to compare.
  • Test on another browser to rule out browser handling.

A key is flagged as stuck

  • Release all keys and press the flagged key again cleanly.
  • Clean around the key switch or cap.
  • Compare on another device to separate hardware from browser handling.

A browser shortcut fires instead of the test

  • Keep the test area focused before pressing.
  • Some OS-level combinations cannot be intercepted; test those keys individually.

Only a few keys register at once

  • This is normal key rollover on many membrane keyboards.
  • For full N-key rollover, use a keyboard that advertises NKRO.

Related Diagnostics

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