DisplayToggle 1.0

First release.

A menu bar app that turns the Mac's built-in display off while an external monitor stays on, plus a zero-dependency Python CLI.

Install: download the .dmg, drag the app to Applications.

The app is ad-hoc signed and not notarized, so Gatekeeper blocks the first launch. Right-click the app and choose Open, or run:

xattr -dr com.apple.quarantine /Applications/DisplayToggle.app

Requires macOS 13 or later. Verified on macOS 27 (Apple Silicon).

Notable

• Black-screen protection: refuses to turn off the built-in display unless another real display is lit, and restores it automatically when the external display is unplugged
• Correctly ignores the virtual display macOS conjures up when every physical display is gone — the thing that makes naive implementations leave you staring at a black screen
• Warns before turning off the display when it is the main one, and offers to move the main display first