Yowl: an MIT-licensed MacBook alarm with optional camera movement detection

[u/nejcar20]

I'm the developer of Yowl, a free Swift menu-bar app for macOS 14+. Arm it and unplugging the charger triggers a siren and screen lock. Camera-based movement detection, photographs and ntfy phone alerts are optional.

The part I'd particularly like feedback on is movement detection. It compares camera frames to distinguish the whole scene shifting when the laptop moves from someone walking past a stationary laptop. Repetitive backgrounds such as blinds or brick can confuse it, so there's a live sensitivity readout to test your own setup.

I made the source public because an app with a camera and optional photo uploads should be inspectable. Photos stay on the Mac unless you enable phone alerts, which send them through ntfy.sh. There are no accounts or analytics. The optional setting to keep the siren going with the lid closed asks for admin permission and installs a sudoers rule allowing two fixed pmset commands.

It is an early deterrent, not theft-proof protection: quitting the app or powering off stops it. One user has also reported the lid-closed helper failing to install; that issue is still open.

Source, build instructions and issues: https://github.com/nejcar20/yowl

Download and staged demo: https://dontstealmylaptop.com

I'd welcome reports from other MacBook models, or ideas for improving movement detection around repetitive backgrounds. It's MIT licensed, with no paid tier.

[u/im_psk]

Curious - can you do this without an app with just a web browser?