Touch Screen Tester
Press Start, then draw anywhere on the screen. Each finger gets its own color, a counter shows how many touches your screen tracks at once, and gaps in the trails expose dead zones.
The test runs full screen. Draw with one or more fingers (or a pen or mouse) — every touch leaves its own colored trail, so dead zones and broken multi-touch show up immediately.
About this tool
What the touch tester shows
Every finger, pen, or mouse press gets its own color and leaves a trail wherever the screen registers it. Sweep slowly across the whole surface: spots where the trail breaks or never appears are dead zones; jagged lines where you drew straight indicate a faulty digitizer.
The counter shows how many touches the screen tracks at once. Most phones report 10, many laptop touchscreens 5 or 10 — if a finger stops drawing when you add another, you have hit the panel's real multi-touch limit.
Testing a stylus
Pens that report pressure draw thicker lines the harder you press, so slow strokes with rising pressure should thicken smoothly. Jumps in thickness or gaps at light pressure point to a pen or driver issue rather than the panel.
Full screen on iPhone
iPhone Safari does not allow web pages to enter true full screen, so there the tester covers the whole browser viewport instead — the address bar may stay visible. Android, iPad, and desktop browsers get real full screen.
Everything runs locally in your browser; nothing you draw is uploaded or stored.