Use your phone as a mouse jiggler

How to set it up

1. On your computer, scan the QR code with your phone camera, or type this page's address on the phone.
2. On the phone, set brightness high and pick a pattern. Stripes or Speckle are good first tries.
3. Choose a motion. “Small circles” keeps the cursor roughly in place; “One direction” moves it steadily and it may reach the edge of the screen.
4. Set a timer if you want it to stop by itself, then press Start full screen.
5. Rest the mouse flat on the phone screen. Do not press any button.
6. Check on the computer that the cursor moves (see the sensor check below). To stop, tap the screen and press Stop, or press Esc on a keyboard.

While the pattern runs, the page also asks the phone for a screen wake lock so the phone display does not go dark. If the phone's browser does not support it, adjust the timeout as described for Android or iPhone and iPad.

Why a moving picture can move the cursor

An optical or laser mouse contains a tiny camera that compares pictures of the surface under it many times per second. When the texture appears to shift, the mouse reports movement. A moving pattern on a screen can produce that shift without the mouse moving.

It is not reliable with every mouse. Mouse makers advise against glass and other see-through or reflective surfaces^[1], because the sensor relies on surface texture and glass is almost completely flat^[2]. A phone screen is glass over a lit image, so results vary with the sensor, the screen coating, the brightness and the pattern.

This is real input as far as the computer is concerned, because it comes from the mouse. It is still visible to anyone looking at the desk, and patterns of perfectly regular movement can be flagged by monitoring software (see what can be detected).

Check whether your mouse responds

1. Open this page on the computer as well and move the cursor into the Sensor check box.
2. Start the pattern on the phone and place the mouse on it without touching the buttons.
3. Within a few seconds the box should say Movement detected and count events and pixels. If it stays on “No movement”, the sensor is not reading the pattern.

The box can only see movement while the cursor is over it, so “Small circles” is the best motion for testing. If nothing is detected, try in this order: raise brightness, switch to Stripes or Speckle, change the speed, wipe the screen, and lift the mouse slightly at the front so the sensor sits flat. Some mice simply will not track on glass. The troubleshooting guide lists more checks.

What tends to work, and what does not

This method moves the cursor, unlike the browser keep-awake tool that only keeps a display on. If you want to understand the difference between the two families of tools, read what a mouse jiggler is.

Battery, heat and comfort

• A bright screen that stays on uses battery quickly. Plug the phone in for long sessions and use the timer.
• Some phones dim or limit brightness when they get warm or when battery saver is on, which can stop the sensor from tracking.
• The patterns move smoothly and never flash the whole screen. If motion bothers you, look away from the phone, or rely on the browser tool instead.
• If your device asks for reduced motion, the preview stays still and nothing moves until you press Start.