Keyboard chatter test
Free, runs in your browser. Type below and any key that fires twice from one press turns red, with the millisecond gap that gave it away. Then fix it, which most keyboard testers cannot do.
Click here, then type
Type normally, or tap the key you suspect at a comfortable pace. Mashing it as fast as you can will look like chatter.
Nothing you type leaves this page. Already running ChatterFix? Pause it first, or it will block the duplicates before the browser can see them. Tab moves focus out of the tester.
How to test your keyboard for chatter
- Click the keyboard above so it starts listening.
- Type a normal sentence or two, or tap the key you suspect at a comfortable pace. Do not mash it as fast as you can, because that looks like chatter to any test.
- Watch for a key turning red. Red means a second press arrived too soon after you let go for a finger to have done it.
- Read the millisecond figure. That gap is the evidence, and it is also the number you need to fix it.
Nothing is uploaded and nothing is recorded. The page only looks at the timing between presses, never at what you type.
What the numbers mean
Every time you release a key and press the same key again, this page measures the gap. That gap is the whole test.
A human finger is slow. Even quick typists rarely get the same key down again inside 60 milliseconds, and doing it under 30 is not really possible on purpose. So when a key reports a second press 4 or 9 or 15 milliseconds after you let go, no one pressed it. The switch did.
Why a key types twice
Keyboard chatter, double typing, key bounce and switch bounce are all the same fault under different names. The metal contacts inside a key switch physically bounce when they meet. On a new switch the bounce settles in well under a millisecond, and the keyboard's firmware is built to ignore anything that fast. As the contacts wear, or pick up dust and oxidation, the bounce lasts longer than the firmware expects. One press gets reported as two, and you get "hellllo" instead of "hello".
It is almost always one specific key rather than the whole keyboard, because it is one specific switch that has worn. That is why the keys above are scored separately, and why the fix works best when it is applied to the bad key alone.
How to fix keyboard chatter
There are three real options. Replace the keyboard, which is certain but costs money. Replace or clean the one switch, which works if the board has hot-swap sockets or you are comfortable with a soldering iron. Or filter it in software, which is free and takes a minute.
ChatterFix does the third one, and it is the part most keyboard testers leave you to solve on your own. It watches for a press arriving too soon after a release on the same key and drops it, leaving everything else untouched. Set it to the millisecond figure this test gave you, on the key this test flagged, and the rest of the keyboard carries on unchanged. It runs in the menu bar on macOS and the system tray on Windows, it is free, and it makes no network requests at all.
Questions
How do I test my keyboard for chatter?
Click the keyboard on this page and type normally for a few lines, or tap the key you suspect at a comfortable pace. The test measures the gap between each key's release and its next press. A gap under about 30 milliseconds is too fast to be a human finger, so it is chatter from a worn switch.
Is keyboard chatter the same as double typing?
Yes. Keyboard chatter, double typing, double keystrokes, key bounce and switch bounce all describe one physical fault: a single press being reported twice because the switch contacts bounce for longer than the keyboard's firmware expects.
What causes keyboard chatter?
Wear, dust and oxidation on the metal contacts inside a key switch. A new switch settles in well under a millisecond and the firmware ignores the bounce. An old or dirty one bounces for longer than the firmware allows for, so the press gets counted twice.
Is a double press always the keyboard's fault?
Not always, but the timing gives it away. Intentional double taps of the same key almost never come faster than 60 milliseconds, even from quick typists. Chatter usually lands under 30. If this test shows repeated gaps in single digits on one particular key, that key is chattering.
Can keyboard chatter be fixed without replacing the keyboard?
Usually, yes. A software filter ignores any second press that arrives too soon after a release, which removes the symptom completely without touching the hardware. Cleaning the switch with contact cleaner sometimes helps too. Replacing the switch or the keyboard is the last resort rather than the first.
Does the test work if ChatterFix is already running?
No. ChatterFix blocks the duplicate press before the browser can see it, so the test will look clean. Pause ChatterFix from the menu bar or system tray first, run the test, then turn it back on.