Keyboard Test — free online key tester

N-key rollover (NKRO) is the number of keys a keyboard can register pressed simultaneously. Cheap membrane keyboards cap at 2 or 3 keys before additional presses are ignored — that means in games requiring W + Shift + Space + E to sprint-jump-interact, one of those keys will be dropped. Gaming mechanicals advertise 6KRO (six keys plus modifiers always work) or full NKRO. USB-HID protocol caps at 6KRO unless the keyboard implements a custom NKRO descriptor; PS/2 keyboards historically supported true unlimited NKRO.

Ghosting is when pressing a specific combination of keys produces phantom keypresses (extra keys firing) or fails to register one of the pressed keys. It happens because cheap keyboards use a matrix circuit where individual keys share rows and columns — certain combinations create ambiguous signals the controller cannot resolve. The classic example is W + A + S in games: many cheap keyboards drop S when W and A are both held, causing failed backward strafes. Mechanical keyboards typically use individual key diodes which eliminate ghosting.

Browsers fire keyboard events only on the focused element, for security and predictability. If you press keys while another window or input field has focus, our tester receives nothing. The visual keyboard area is a focusable container with a tabIndex attribute — clicking it gives it focus and starts capture. A violet border indicates focus is active; if the border disappears, the page lost focus and keys will not register.

Some keystrokes are intercepted by the operating system before reaching the browser. Cmd+Tab on macOS, Win+L on Windows, multimedia keys on some keyboards, and global hotkeys for accessibility features all route directly to the OS. Browsers receive nothing, so no test can detect them. This is not a keyboard fault. If you need to verify these keys work, test them through their OS function (Win+L should lock the screen; Cmd+Tab should switch windows).

NKRO requires deliberate testing. Most natural typing peaks at 3-4 simultaneous keys even on an NKRO board because we rarely hold many keys at once during normal use. To verify true NKRO, deliberately press 6 or more keys simultaneously — try pressing A, S, D, F, J, K, L all at once. If they all register on the visual keyboard, you have at least 7KRO. NKRO over USB also requires Windows or Mac to be in N-key mode (some keyboards have a 6KRO/NKRO switch on the back).

Chatter is when a single physical keypress registers as two or more keypresses, caused by mechanical switch contact bounce or oxidized contacts. It is the opposite of a stuck key — chatter produces extra characters, stuck keys produce repeated characters. Our v1 does not directly detect chatter (it would require keystroke-interval analysis on the same key, which we may add in v1.1). For now, if you suspect chatter, type a few sentences in any text field and look for unwanted duplicate characters from single keypresses.

No. The four layouts (ANSI 104, ISO 105, TKL 87, 60% Compact) define which keys count toward coverage scoring, but our tester captures every key code your keyboard sends. If you have a non-standard keyboard (split, ergonomic, ortholinear, or a custom QMK build), pick whichever layout most closely matches yours — coverage will be slightly off but all four signals still work. Choose 60% Compact if your keyboard has no F-row or arrows, TKL if no numpad, ISO if you have an extra row-5 key.