What it detects
For each key: how many times you pressed it, how many presses came faster than your threshold, the chatter rate and the shortest gap. Keys with chatter are shaded red on the virtual keyboard.
Keyboard Switch Fault Check
Key Chatter Test
Find the keys that type two letters when you press them once. Type slowly across the keyboard and the test flags any second press that comes too fast to be yours, then marks the problem keys on a heat map.
Every Key, Any Keyboard
Adjustable 30–150 ms Threshold
Heat Map of Problem Keys
Holding a Key Never Counts
Not started
Chatter threshold
Two presses of the same key closer together than this are flagged as chatter. Holding a key down (auto-repeat) is ignored.
Press Start, then type
Press each key once at a normal pace, or tap a suspect key about once per second. Keys pressed while the test is running do not type anywhere else.
Start the test and type to check your keys.
Pressed, no chatterChatter detected (darker = more often)
Key labels
Fn+Vol
Mute
Vol-
Vol+
Prev
Play
Next
Music
Web
Back
Fwd
Refresh
Close
Search
Star
Mail
Cal
Phone
ESC
F1
F2
F3
F4
F5
F6
F7
F8
F9
F10
F11
F12
~`
!1
@2
#3
$4
%5
^6
&7
*8
(9
)0
_-
+=
Backspace
Tab
Q
W
E
R
T
Y
U
I
O
P
{[
}]
|\
Caps Lock
A
S
D
F
G
H
J
K
L
:;
"'
Enter
Shift
Z
X
C
V
B
N
M
<,
>.
?/
Shift
Ctrl
Win
Alt
Space
Alt
Win
Menu
Ctrl
Prt Sc
Scr Lk
Pause
Insert
Home
Pg Up
Delete
End
Pg Dn
↑
←
↓
→
Num
/
*
-
7
8
9
4
5
6
+
1
2
3
0
.
Enter
Results by key (worst first)
Keys you press will be listed here.
About the Key Chatter Test
• Key chatter is when one press of a key is sent to the computer as two or more presses, so you get doubled letters like “thhe”.
• The test times every key press and flags a second press of the same key that arrives sooner than the threshold. Real repeated typing is almost always slower than that.
• Holding a key down makes your operating system repeat it. Those auto-repeat events are marked by the browser and ignored, so a long press never counts as chatter.
• Problem keys turn red on the virtual keyboard, and the table lists every key you pressed with the worst ones first.
• Chatter usually starts on the keys you use most, such as E, space, backspace or WASD, so test those for longer.
• The home page keyboard tester flags chatter too; this page goes deeper with per-key rates, an adjustable threshold and a heat map.
How to read your key chatter results
Chatter is a timing fault: one physical press reaches the computer as two. These notes explain the numbers and what to try next.
Test with the keyboard connected the way you normally use it, and close macro or remapping software while testing so it cannot add presses of its own.
Why keys start to chatter
Oxidized or dirty switch contacts, dust or spilled liquid, worn springs, and firmware debounce set too low are the usual causes. Wireless interference can also cause dropped or doubled keys on some boards.
How to fix it
Clean the switch with compressed air and isopropyl alcohol, re-seat or swap a hot-swap switch, raise the debounce time in QMK, VIA or the maker's software, update the firmware, or replace the switch.
How to judge the result
While typing slowly, one flagged press in a few hundred is worth watching; several per hundred on the same key means the switch is failing. Gaps under about 30 ms are almost never human. Retest after every fix.
Browser and device limits
The browser only sees presses after the keyboard firmware and operating system have handled them, so it cannot see bounce the firmware already filtered. On-screen keyboards cannot be tested.
Key Chatter Test FAQ
What key chatter is, how to confirm it and how to fix it
What is key chatter?
Chatter is a switch fault where one key press produces two or more key presses. You type “hello” and get “helllo”. It comes from contacts that bounce, usually because of dirt, oxidation or wear, or from firmware that filters bounce too little.
What threshold should I choose?
50 ms suits most people. Switch bounce usually shows up as gaps under 30 ms, while even very fast typists rarely press the same key twice within 50 ms. Use 30 ms if you type extremely fast, and 80–150 ms when you tap one suspect key slowly.
Why doesn't holding a key count as chatter?
When you hold a key, your operating system repeats it on purpose after a short delay. Browsers mark those events as repeats, and the test skips them, so only separate presses are compared.
How do I fix a chattering key?
Blow out dust, then clean the switch with isopropyl alcohol while pressing it repeatedly. On a hot-swap board, swap the switch. Many QMK and VIA keyboards let you raise the debounce time. If none of that helps, replace the switch or use the warranty.
Could the problem be software instead of the keyboard?
Sometimes. Macro software, key remappers and remote-desktop tools can inject extra key presses. Test the keyboard on another computer, or with its software closed: if the chatter disappears, the cause is software.
Need More Help?
If your results look strange or you are unsure what they mean, contact our support team.
Contact SupportKeyboard Guides & Resources
Go deeper with our expert guides - testing methods, troubleshooting, and buying advice.
How to Fix Keyboard Chatter: Keys That Type Twice
Keys typing two letters from one press? Confirm chatter with a test, rule out settings, clean the switch, raise debounce in QMK or VIA, swap or replace the switch, or use the warranty.
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