Alarmist LiDAR Motion Detector

*Requires LiDAR sensor: iPhone 12 Pro or newer, iPad Pro (2020 or newer). Must be a Pro version to work.*


I'm an indie developer in Portland, Oregon. I built Alarmist because I wanted a simple motion alarm that works in complete darkness. LiDAR uses infrared, not visible light, so it detects motion even in pitch black conditions.

- Extra alert layer while sleeping in unfamiliar places
- Motion detection where cameras would need light
- Doorway monitoring when you want to know if someone enters

How it works:


1. Place your device on a stable surface, aimed at the area you want to monitor
2. Configure the detection zone and sensitivity (or use defaults)
3. Arm the app
4. Keep the app in the foreground with the screen on


If motion is detected in the monitored zone, you get an immediate loud alarm (ignores Silent Mode), optional flashlight, and optional photo capture.


LiDAR measures actual depth. A person walking through a space creates large, sustained depth changes that are easy to distinguish from noise. This works reliably in conditions where camera-based detection would struggle.


Important limitations:

- Device must stay plugged in for extended monitoring

- App must remain in foreground with screen on
- Screen lock or switching apps stops monitoring
- Test thoroughly in your specific environment before relying on it


Not a substitute for proper security systems. This is one tool among many. Test it. Understand how it works. Do not rely on it exclusively for safety.


I called it Alarmist because the name suggests someone who overreacts to danger. When you're trying to sleep, a little overreaction is the point.