Games

N-Key Rollover Test - Keyboard Ghosting & NKRO Checker

Test your keyboard's simultaneous key press (N-key rollover) in the browser. Shows currently pressed keys and count. Distinguishes Left/Right Shift/Ctrl/Alt/Meta.

Ready. Press multiple keys simultaneously.
0
Currently pressed key count (simultaneous)
Keyboard diagram (pressed keys light up)
Esc
Escape
F1
F1
F2
F2
F3
F3
F4
F4
F5
F5
F6
F6
F7
F7
F8
F8
F9
F9
F10
F10
F11
F11
F12
F12
`
`
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
0
0
-
-
=
=
Backspace
Backspace
Tab
Tab
Q
Q
W
W
E
E
R
R
T
T
Y
Y
U
U
I
I
O
O
P
P
[
[
]
]
\
\
Caps
CapsLock
A
A
S
S
D
D
F
F
G
G
H
H
J
J
K
K
L
L
;
;
'
'
Enter
Enter
Shift
Shift L
Z
Z
X
X
C
C
V
V
B
B
N
N
M
M
,
,
.
.
/
/
Shift
Shift R
Ctrl
Ctrl L
Alt
Alt L
Meta
Meta L
Space
Space
Meta
Meta R
Alt
Alt R
Ctrl
Ctrl R
ArrowLeft
ArrowDown
ArrowUp
ArrowRight
* Based on US layout (some key positions differ on JIS/ISO keyboards) / CapsLock is ignored
Keyboard actions such as Space/Arrows/PageUp-Down/Home-End/Backspace/Tab are blocked (mouse wheel is OK)

What is the Simultaneous Key Test?

This page is a test that visualizes simultaneous key presses (multiple key input at once) in your browser. Pressed keys light up on the keyboard diagram, making it easy to check whether your keys are actually registering during gaming (e.g., movement + jump + crouch) or shortcut operations, and whether certain combinations are dropping.

What This Test Shows

It tallies and displays the keys currently treated as pressed based on key inputs received by the browser. What you see here is the result of inputs that reached the OS/browser. Rather than focusing on the number alone, the most useful approach is to check whether the key combinations you actually use are dropping.

How to Use

Simply press multiple keys simultaneously after opening this page. Keyboard-triggered actions such as Space, Arrows, PageUp/Down, Home/End, Backspace, and Tab that would cause scrolling, navigation, or focus changes are blocked as much as possible.

Important Notes

Since this page displays browser events, it cannot be used to definitively determine keyboard specifications as a standard. Results may also be affected by OS settings, power saving modes, app focus state, and browser state.
CapsLock (including JIS Eisu/Kana variants) is completely ignored to stabilize simultaneous key detection, as its behavior varies greatly across environments.

Frequently Asked Questions (FAQ)

Q. Is it abnormal that my simultaneous key count stops around 7?
A. Not necessarily. Which key combinations pass or drop depends on the keyboard's wiring (matrix), the specific model, and the key combination being pressed. Rather than judging by the number alone, we recommend checking whether the combinations you actually use (e.g., W+Shift+Space) are dropping.
Q. Is it intended that CapsLock does not respond?
A. Yes. CapsLock and JIS Eisu/Kana variants produce inconsistent events across environments and tend to disrupt simultaneous key detection. For stability, they are not counted, not highlighted, and not stored in the internal Map.
Q. Can I use this with a non-US layout (e.g., JIS, ISO)?
A. Yes. The keyboard diagram is based on US layout so some key positions may differ, but key press detection still works. It is recommended to use this tool to check which key combinations tend to drop.