Keyboard tester

How to test a keyboard

1. Pick the layout that matches your keyboard: ANSI (wide Enter, long left Shift, common in the US), ISO (tall Enter, an extra key next to left Shift, common in Europe) or Mac. Choose Full if it has a number pad, TKL if not. The page guesses from your system and switches by itself when you press the extra ISO key or a number-pad key.
2. Click the keyboard drawing once. Tab, Space, the arrows, F1–F12 and Backspace are now caught by the page instead of scrolling or going back.
3. Press every key once. Each lights while held and stays marked after; the Keys tested counter climbs. A key that stays dark sent nothing to the page.
4. Hold letters together for the rollover test and read the verdict.
5. Tap a key that double-types 20 or 30 times and read the chatter list.
6. To leave the test area with the keyboard, hold Esc for a second; or just click elsewhere.

What the numbers mean

Every key press is a keydown event, every release a keyup. The log shows the two names a browser gives a key: key is what the key types in your current language (a, A with Shift, é on a French layout), and code is the physical position, named after the US key in that spot (KeyQ is the key left of W, even on an AZERTY board where it types A). The drawing lights keys by code, so it works whatever language your system uses, although the printed legends on your keys may differ from the drawing's. Location tells left from right Shift, Ctrl and Alt, and the number pad from the top row. Repeat is yes for the auto-repeat events the system sends while a key stays down, typically 20 to 30 per second after a wait of about half a second (both are system settings). Held is the time from keydown to keyup; a normal tap is 60 to 150 ms.

Rollover: how many keys at once

Cheap keyboards wire keys in a grid and can only tell a few apart at the same time; press more and extra keys are dropped. A keyboard on the standard USB report can send 6 ordinary keys plus the modifier keys (Shift, Ctrl, Alt, Win/command, left and right), so the page counts modifiers apart. The verdict: 2-key to 5-key if that is the most it ever lit, 6-key at exactly 6 (the USB limit, called 6KRO), N-key at 7 or more. Worked example: you hold A, S, D, F, J, K and L and only six light; the tile shows 6 and the verdict is 6-key. Hold Shift as well and it still says 6; the total including modifiers is shown on its own line.

A low number is only proven for the keys you tried. Gaming keyboards often have full rollover on the letters but not on the number pad, and a board can be fine on A S D F and still block W A Shift, so try the groups you use.

Chatter: a key that types twice

A key switch is a pair of metal contacts. When they wear, oxidise or get a crumb in them, they can bounce: one press closes, opens and closes again within a few milliseconds, and the keyboard reports two presses. The page remembers when each key was last released. If the same key goes down again less than the threshold later (30 ms by default, change it from 5 to 150), the press is flagged with the measured gap, for example KeyE, 6 ms after release. Deliberate double taps by a person are rarely under about 60 ms, so a gap under 20 ms is almost always the switch. Many keyboards already filter bounce in their firmware, so a chattering key is often worse than this page shows, not better. Auto-repeat while holding a key is not counted.

Keys and shortcuts no page can catch

The browser or the operating system acts on these before a web page sees them, so the page cannot test them as keys and they may close or switch away from it:

• Ctrl+W / ⌘W, Ctrl+T / ⌘T, Ctrl+N / ⌘N: close tab, new tab, new window
• Ctrl+Shift+T, Ctrl+Shift+N, Ctrl+Tab, Ctrl+PgUp/PgDn: reopen and switch tabs, private window
• Alt+Tab / ⌘Tab, Alt+F4 / ⌘Q, ⌘H, ⌘Space: switch, quit or hide apps, Spotlight
• Win alone, Win+L, Win+D, Ctrl+Alt+Del: Windows keeps these (the Win key itself usually still lights)
• Esc while in full screen: leaves full screen, unless the keyboard is locked

In Chrome and Edge the Full screen + lock keys button uses the browser's Keyboard Lock, which lets most of the shortcuts above reach the page while it stays full screen; hold Esc to leave. Other browsers do not offer it and the button stays hidden.

What it cannot do

• It cannot see keys the operating system or the keyboard keeps for itself: Fn (handled inside the keyboard), most media, volume and brightness keys, and on some systems Print Screen, which Windows often shows to the page as a release with no press (the log says "up only" and the key is still marked).
• On a phone or tablet it tests a connected hardware keyboard only. The on-screen keyboard does not report physical keys.
• It cannot repair or remap anything, and it cannot see keys a keyboard's own software has remapped or turned into macros; it shows what arrives.
• Chatter shorter than the keyboard's own debounce filter is hidden by the keyboard before the page could see it.
• Only one keyboard at a time: if two are connected, the page cannot tell which one a key came from.

Privacy

Key presses never leave your device and nothing is saved. The page sends an anonymous page-view count and one of two fixed words, kbd-start and kbd-rollover; never a key, a code or a number.

Questions

How do I test my keyboard online?

Open this page, click the keyboard drawing once so it has focus, and press every key in turn. A key lights while you hold it and stays marked afterwards, and the counter shows how many of the keys on the drawing have worked. A key that never lights did not reach the page: it is broken, or the operating system kept it.

Does this keyboard tester work on a Mac?

Yes. On a Mac the page starts with the Mac layout (command, option, control, fn), and switches to the Mac ISO shape when you press the key left of Z. The fn key and the media keys are handled by macOS and never reach a web page, and macOS sends no key-release for a letter released while command is held, so the page releases those letters when you let go of command.

How do I test keyboard rollover (how many keys at once)?

Hold down letter keys one after another without letting go, for example A S D F then J K L. The Most at once tile shows the most ordinary keys registered together, with Shift, Ctrl, Alt and Win or command counted apart. 2 to 5 means limited rollover, 6 is the standard USB limit (6KRO), 7 or more is N-key rollover. Try a few different groups: some boards block particular combinations.

Why does my keyboard type double letters, and how do I check for it?

Double typing is usually chatter: a worn or dirty switch makes contact twice for one press. Tap the suspect key normally twenty or thirty times. The page flags any press that starts less than the chatter threshold (30 ms by default) after that key's previous release, with the gap measured. People rarely re-press one key in under about 60 ms, so a few-millisecond gap is the switch, not you.

Can I test a keyboard on a phone or tablet?

Only a hardware keyboard connected by Bluetooth or USB. The on-screen keyboard of a phone does not report which physical key was pressed, so it cannot be tested here.