Hot-swappable mechanical keyboard
A bad switch can be replaced without soldering, which makes a chattering key a quick fix.
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Keyboard Tester: Check Every Key Online
Press each key and watch it light up. The tester also counts how many keys you can hold at once and flags a key that fires twice in a blink.
Keys tested 0 · Most keys held at once 0 · Chatter none seen
Keyboard-only tip: press Esc three times in a row to leave the tester.
Event log
Runs in your browser. Nothing leaves this page.
Quick answer
Click the board, press keys, and each one lights while held and stays marked once tested. The rollover counter shows the most keys held at once, and a key that repeats within 30 ms is flagged as possible chatter.
How to use the Keyboard Tester
Pick your layout
Choose full, TKL, 75% or 60% so the on-screen board matches yours.
Click, then press keys
Click the board to start capturing. Tested keys stay marked so you can see what is left.
Check rollover and chatter
Hold several keys at once, then read the rollover and chatter counters. Reset to start over.
How the keyboard tester works
While the board has focus, the page reads every key event your browser receives and marks the matching key by its physical position code, so it works the same with any language layout. While you are testing, the page keeps the browser from acting on keys like Tab, F5 or Space. Press Esc three times in a row to hand the keyboard back, or click anywhere outside the board.
Some keys never reach the browser: the Fn key on most keyboards, and system shortcuts like Windows+L, are handled by the keyboard or operating system. Those will not light up even on a perfect board. Every key that does arrive also appears in the event log, even if it is missing from the on-screen layout.
Rollover and chatter explained
Rollover is how many keys a keyboard can report at once. Hold keys one by one and watch the counter: if it stops rising while you keep adding keys, your keyboard (or its connection) has reached its limit. A USB keyboard in basic mode reports a handful of keys; gaming boards usually report many more. Browsers and operating systems can also cap what you see, so treat the count as "at least this many".
Chatter is when one physical press registers twice. The tester flags a key that is pressed again less than 30 ms after it was released, which is faster than a person can repeat a key. A single flag can be a fumble; a key that is flagged again and again points to a switch worth cleaning or replacing.
| Result | What it suggests | What to try |
|---|---|---|
| A key never lights | The key, its switch or its connection is not sending a signal, or the key is not forwarded to browsers (Fn). | Check it in another app, clean around the switch, test on another USB port. |
| Rollover stops at 6 | Basic USB rollover mode, or a keyboard limit. | Check for an N-key rollover setting, and try a wired connection. |
| Same key flagged repeatedly | Possible switch chatter. | Clean the switch or hot-swap it if your board allows. |
| Key lights without being pressed | A stuck key or debris. | Check under the keycap; test again after cleaning. |
Gear that helps
Category searches on Amazon, picked because they relate to what this tool checks. Compare options and read the listing before you buy.
Switch tester
A sampler of switch types, handy before you commit to linear, tactile or clicky.
Search on AmazonKeycap puller
Lets you lift keycaps to clean under a key that is not registering.
Search on AmazonAmazon Associates affiliate links: we earn from qualifying purchases. See our affiliate disclosure.
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Frequently asked questions
How do I test my keyboard keys online?
Click the on-screen board and press each key. A key lights while you hold it and stays marked once tested. Any key left unmarked at the end is one your browser never received.
What is key rollover?
Rollover is the number of keys a keyboard can report as pressed at the same time. Basic keyboards cap at around six; many gaming boards report many more, which matters for fast combos.
How do I test for ghosting?
Hold several keys at once, especially groups like W, A and D plus Space or Shift. If the rollover counter stops rising or a held key goes dark, your keyboard dropped it. Try again wired, since some wireless modes limit keys.
What does chatter mean?
Chatter, or switch bounce, is when one press registers twice. This tool flags a key pressed again within 30 ms of release, faster than a person can repeat a key.
Why doesn't my Fn key light up?
Most keyboards handle Fn inside the keyboard itself and never send it to the computer. That is normal and not a fault.
Why do some keys trigger browser actions?
While the board is focused, the tester stops browser shortcuts so you can test them. Press Esc three times in a row to return control, or click away from the board.
Is anything I type recorded?
No. Key events are read in your browser tab and the log is cleared when you reset or leave. Nothing is sent anywhere.
This article reflects independent editorial research and disclosed buying criteria, not hands-on lab testing or manufacturer sponsorship. Some links on this page are Amazon Associates affiliate links; see our affiliate disclosure.