Can this test N-key rollover or ghosting?

Only as far as the browser can see. It counts the keys the browser reports as held at the same time. A keyboard or the operating system can drop or block combinations before they reach the page, so the count cannot confirm hardware rollover or detect switch faults.

Why does a key not light up?

Some keys never reach web pages: Fn is usually handled by the keyboard itself, and the operating system or browser can reserve keys and shortcuts such as Print Screen, Alt+Tab or Command combinations. Keys that are not on the ANSI layout, such as ISO or media keys, appear under Other keys.

Does it record what I type?

No. Key events are read only while the test area is focused, processed in your browser and never stored or sent. Only the latest event is shown.

Keyboard Tester

Runs locally in your browser

Check every key on a physical keyboard in your browser

Click the keyboard or select Start test to begin.

Keyboard

Not tested
Pressed
Tested

Keys are captured only while this area is focused.

Results

Tested keys

0 of 104

Browser-observed simultaneous keys

Held now: 0
Session peak: 0
Events: 0

Active keys:No keys held

Counts keys the browser reports as held at the same time. Some keyboards drop or block combinations before the browser sees them, so this cannot confirm hardware rollover.

Latest event

No key events yet

Click the keyboard area, then press keys.

Shows only what the browser receives. The OS or browser can reserve some keys and shortcuts (for example Fn, Print Screen or Windows/Command combinations), so they may never reach the page.

Mouse TesterCheck mouse buttons, wheel, double clicks and CPS in your browser Device & Browser InformationSee what your browser exposes for support and debugging User Agent ParserParse any User-Agent string into browser, OS, device, and bot details

What it checks

Keyboard Tester shows an ANSI full-size keyboard (function row, main keys, navigation cluster, arrows and numpad). Each key lights up while the browser reports it as pressed and stays marked as tested after release, so you can work through every key and spot positions that never register. The results show the latest event, the keys held now and the session peak of browser-observed simultaneous keys.

Physical position, not typed character

Keys are matched by KeyboardEvent.code, which names the physical position (for example KeyA or ShiftRight) whatever layout or language is active. The latest event also shows key (the typed value), location (Standard, Left, Right or Numpad, which separates left and right modifiers) and repeat (true while a held key auto-repeats). The deprecated keyCode and which fields are kept under Legacy fields for debugging older code.

Browser limits

A web page only sees events the operating system and browser pass on. Fn, some media keys, Print Screen and system shortcuts such as Alt+Tab or Command+Tab may never arrive, and macOS does not send key releases for other keys while Command is held, so the tester releases them when Command is released. The simultaneous-key count is what the browser observed; it cannot measure hardware rollover, ghosting or switch quality. Keys that are not on the ANSI layout are listed under Other keys.

Privacy

Key events are read only while the test area is focused and are processed in your browser. Nothing is recorded, stored or sent, and only the latest event is kept on screen. Leaving the area, switching tabs or selecting Stop test releases every held key.