To test your keyboard, open a keyboard test, click into it, and press every key. Each working key lights up on an on-screen layout. Any key that never lights is not registering. The free keyboard test shows the key code for each press and helps you spot stuck keys and ghosting.
That covers the basics. Here is how to do a thorough check and read what you find.
When a keyboard check is worth it
Three moments make this worth a minute of your time. Before buying a used laptop or keyboard, so a dead key does not surprise you after the money has changed hands. After a spill or a clean, to confirm everything still works. And when a single key has started misbehaving, to prove it is the key and not your typing.
How to test your keyboard
Step 1: Give the tester focus
Click the keyboard area on the keyboard test so your presses go to it rather than scrolling the page. Then start pressing.
Step 2: Work across every key
Go methodically: the number row, the letters, the modifiers, the function keys, the arrows. A key that lights up green has registered. A key that never lights, no matter how hard you press, is not reaching the computer. Do not forget the modifier keys like Shift, Ctrl and Alt, which are easy to skip and annoying to discover broken later.
Step 3: Check for sticking and ghosting
Watch for a key that stays lit after you release it, which suggests it is physically sticking. Then hold several keys at once, three or four together, and count how many light up. This tests whether your keyboard can report fast combinations, which matters for gaming and shortcuts.
Reading the key code
Each press shows a code that names the physical key, such as KeyA or Enter. This is genuinely useful in two cases. If a key types the wrong character, the code tells you whether the key itself is fine and your layout is simply set to another language. And if you are remapping keys in software, the code is the name the software needs.
Common faults and what they mean
- A dead key. No light, fails everywhere. The switch or the membrane under that key has failed. On a laptop this usually means a keyboard replacement; on a mechanical keyboard, sometimes a single switch.
- A sticky key. Stays lit, or repeats characters. Often crumbs or dried liquid under the cap. A clean fixes many cases.
- Ghosting. Some keys in a combination do not light. The keyboard cannot report that many keys at once. It is a design limit, not damage.
- Wrong characters. Keys work but type the wrong letters. Almost always a layout set to the wrong language or region.
What the test cannot tell you
A browser test sees what the operating system passes to it, so a handful of special keys, media controls, and some laptop function combinations may be handled before they ever reach the page. If only those keys seem missing, they are probably fine. For everyday letters, numbers and modifiers, the test is reliable.
With the keyboard checked, the natural next step is a mouse test to confirm your other main input works too.