How to use the keyboard test
Click the keyboard panel, or move to it with Tab, until the yellow focus outline and “Keyboard test active” message appear. Press one key at a time to check ordinary letters, numbers, punctuation, arrows and function keys. The matching key on the diagram turns yellow while it is down and remains lightly highlighted after release, so you can see both the current press and the keys already observed. Pressed now lists browser codes for all keys currently held. Last key shows the character or action reported by KeyboardEvent.key, while Last code shows the physical-position identifier from KeyboardEvent.code.
To check combinations, hold two or more keys together, such as left Shift plus A. The current list should contain both codes until each key is released. Left and right Shift, Control, Alt and OS keys have separate positions on the diagram because browsers normally report distinct codes for them. Holding a key may cause repeated keydown events according to the computer’s repeat settings; the status line reports those repeats without adding the same code twice to Keys tested. Use Clear to remove the history and return the readouts to their initial state.
What the results mean
A yellow key means this focused page received a keydown event for that code. A light highlight means the code was received at least once since the last Clear. These are observations, not a hardware diagnosis. Keyboard layouts can change the character in Last key while Last code still describes the same physical position. For example, a layout may produce a different character from the key located at KeyQ. That difference can be normal.
For a practical check, type every letter once, then test the number row and punctuation. Next hold the left and right modifier keys separately and compare the code readout. Finally try a few combinations you use often. If a key seems absent, click the panel again, repeat slowly, and compare it in another supported application before drawing a conclusion.
Focus, shortcuts and privacy
The listener is attached only to the visible test panel. It does not record keys while you use the page header, another tab or another application. Leaving the panel with Tab, clicking elsewhere, switching windows or otherwise losing focus immediately clears Pressed now so a released key cannot remain visually stuck. Tab and Escape keep their normal ability to move away or exit browser modes; the page does not trap focus. Space is prevented from scrolling only while the panel itself is focused so its press can be seen clearly.
All state stays in page memory and Clear removes it. The tool does not save a history, use local storage, send keystrokes to a server, identify a keyboard model or attach a global listener. Avoid typing passwords or other secrets into any keyboard-testing page, even when it says processing is local.
Browser and operating-system limits
A browser receives only the events that the operating system chooses to deliver to the active page. Power keys, firmware shortcuts, screen-brightness controls, secure attention sequences, application switching and some OS or browser commands can be intercepted before this page sees them. Laptop Fn behavior is often handled in firmware and may not appear as its own web key. Browser extensions, accessibility software, input methods and remote-desktop tools can also change what is reported.
Because of these limits, the page cannot certify every switch, measure electrical bounce, prove rollover specifications, detect intermittent faults automatically or test keys outside the displayed common layout. It shows simultaneous events that reach this browser session, but that is not a laboratory measurement of n-key rollover. Recheck suspicious results with the manufacturer’s diagnostic or a qualified repair service.
Frequently asked questions
Why do key and code differ? Key follows the active layout and modifier state; code follows the physical position. Why does a held key repeat? The operating system generates repeated keydown events after its configured delay. Why did pressed keys clear when I changed tabs? The panel deliberately releases its visual state on blur to avoid a stuck result. Why is an OS shortcut missing? It may be reserved before the page can observe it. Does a highlighted key prove it is healthy? No. It proves only that at least one matching browser event arrived during this session. Does this page store my typing? No; the current set, history set and last event exist only in page memory and are cleared on reload.