Tool

Keyboard tester

Press any key and it lights up on the keyboard below, then stays green once it has worked. The page shows each key's name and code, counts how many keys your keyboard reports at once, and flags a key that registers twice from one press. It picks a Mac or PC layout from your computer, and you can switch.

Test a keyboard in this order

  1. Click the page once, so it receives the keyboard.
  2. Press every key, row by row. Each one turns green as it registers.
  3. Hold down several keys together, such as A, S, D and F with J, K, L and the semicolon, and read most keys held at once.
  4. Tap each key quickly a few times. A red outline marks a key that registered twice.
  5. Copy the report if someone else needs to see the result.

Read the result

  • Green. The browser has seen that key at least once.
  • Blue. The key is held down right now.
  • A red outline. The key registered again within 30 milliseconds of being released, faster than a finger presses twice. Once can be a quick tap. Again and again is a switch that chatters.
  • Gray. Not pressed yet, or a press that never arrived.
  • The line under the key's name. What the browser reported: the key, its physical code, and the HID usage number, which is the number InputConfig stores for that key.

Go row by row and nothing gets skipped. Every key green and no red outline is a healthy keyboard.

How many keys at once

A keyboard that uses the basic USB report sends at most six keys at once, plus the modifier keys. Many laptop keyboards also drop some combinations of three or four keys, which is called ghosting: one key of the group never arrives. A keyboard sold as N-key rollover reports every key. Hold keys down one after another, watch keys held right now, and the number where it stops climbing is your keyboard's limit for that group of keys. Try a second group, because ghosting depends on which keys you combine.

If a key does nothing

Climb this ladder, smallest step first:

  1. Click the page. The page only hears the keyboard while it is the front window.
  2. Check that Catch every key is on. With it off, keys do what they normally do and some never reach the tester.
  3. Hold fn on a Mac. F1 to F12 run brightness, volume and media unless fn is held, or unless you turn on Use F1, F2, etc. keys as standard function keys in System Settings, Keyboard, Keyboard Shortcuts, Function Keys.
  4. Press a modifier on its own. Command, Control, Option, Alt and the Windows key are tested alone, because combinations with them belong to the system and the browser.
  5. Try the key somewhere else. If it types nothing in a text editor either, the switch or the contact under it has failed.

What a web page cannot test

Some presses never reach a web page, on any keyboard. On a Mac that is the fn or Globe key, the brightness, volume and media keys on the top row unless fn is held, and the shortcuts macOS and the browser keep, such as Command Q, Command W and Command Tab. On a PC it is the Windows key in many browsers, Alt F4 and Ctrl Alt Delete. The page also cannot measure how far a key travels or how hard it was pressed. A key that stays gray only in this list is not broken: test it on its own, or in a second app.

Give a spare key a job

A key that works but does nothing, F13 to F19, a numpad, a second keyboard, can do real work on a Mac. InputConfig, the free app I make, can have it open an app, run a macro or type a phrase. It listens to the keyboard and does not block or remap the key itself, so pick keys that type nothing on their own, as F13 to F19 on a Mac explains. Test it here, then give it a job there.

Questions

How do I test my keyboard online?

Open this page, click it once, and press every key. Each key lights while you hold it and stays green once the browser has seen it. A key that stays gray did not register.

Why do some keys not light up on a Mac?

The top row controls brightness, volume and media by default, and macOS keeps those presses for itself. Hold fn while pressing F1 to F12, or switch them to standard function keys in System Settings, Keyboard.

How many keys can my keyboard press at once?

Hold keys down one after another and read most keys held at once. A keyboard on the basic USB report stops at six keys plus the modifiers, and an N-key rollover keyboard keeps going.

What is keyboard chatter?

A worn switch can make contact twice from one press, so one key types twice. The tester outlines a key in red when it registers again within 30 milliseconds of being released.

Related

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Download InputConfig on the Mac App StoreFree. macOS 14 or later. No account, nothing leaves your Mac. Open source on GitHub.