DeskUtilsExternal Display Only
Work on your external display only
External Display Only turns off your Mac’s built-in display while a supported external monitor is connected, so you’re not lighting up both screens.
Toggle from the menu bar
How it works
Available on Apple silicon MacBooks
Available on Apple silicon MacBooks with a built-in display and a native external monitor connected over HDMI, DisplayPort, USB-C or Thunderbolt. DisplayLink, AirPlay, Sidecar, virtual displays and mirrored configurations are not supported. Turning on the utility only starts monitoring — it never turns off the built-in display by itself; that happens only when a supported external monitor is connected. DeskUtils restores the built-in display when the final supported monitor is disconnected, the Mac sleeps, you sign out, or DeskUtils quits.
Permissions
What macOS asks for
No additional macOS privacy permission is required.
How to allow permissions →Questions about External Display Only
Which Macs and monitors does this support?
Apple silicon MacBooks with a built-in display and a native external monitor connected over HDMI, DisplayPort, USB-C or Thunderbolt. DisplayLink, AirPlay, Sidecar, virtual displays and mirrored configurations are not supported.
What happens when I disconnect the external display?
DeskUtils restores the built-in display when the final supported monitor is disconnected, the Mac sleeps, you sign out, or DeskUtils quits.
Does turning it on immediately switch off the built-in display?
No. Enabling the utility only starts monitoring; it turns off the built-in display only once a supported external monitor is connected.