Sensor Phone

Sensor Phone turns a spare Android phone into a monitor for the things you care about — your car, your bike, the front door, or the cat while you're out. HOW IT WORKS You need two devices signed in to the same account. The spare phone runs in Monitor mode and watches. Your current phone runs in Control mode and tells you when something happens. That's the whole setup. No pairing codes, no hub, no extra hardware. WHAT IT WATCHES - Microphone — reacts to noise above the level you set - Camera — detects movement in the frame - Accelerometer — notices when the device is lifted or moved - Gyroscope — picks up rotation and tilt - Battery — warns you before the watching phone runs out You set the threshold for each sensor yourself, with a live reading in front of you. Anything below the line stays quiet. Sensors you don't need stay off. WHEN SOMETHING HAPPENS A push notification usually reaches your phone within seconds — at home on Wi-Fi or anywhere on mobile data. You don't have to keep the app open: alerts arrive even when Sensor Phone is closed and your phone is in your pocket. Every alert is logged with the time and the measured value, so you can see what actually happened rather than guessing. You can also look in live: stream video from the watching phone, or ask it where it is. QUIET HOURS Set time windows where nothing triggers. Useful when you're in the room yourself and don't want an alert every time you move. PRIVACY Nothing is recorded. Only volume levels leave the microphone, never sound. The live video is end-to-end encrypted and exists only while you're watching. It passes through a relay server in Germany that only forwards the packets — it cannot read the content and keeps nothing. Both devices sign in with the same account. There is no invite link and no way to connect to a device you don't control — setup requires the phone in your hand and your own credentials. While the app is watching, that phone shows a notification. Swiping it away stops it — there is no way to hide it and keep watching. Watching someone without their knowledge is illegal in most countries. FREE AND PRO Free: microphone, accelerometer and gyroscope monitoring, alerts, and the last 12 hours of event history. Pro: adds camera motion detection, live video, location on request, battery alerts, webhooks (for example to Home Assistant) and the full event history. REQUIREMENTS Two Android devices. The watching phone should stay plugged in — continuous sensor monitoring uses power. Note: Sensor Phone is not a certified alarm system. Alerts need internet, Google's push service and battery power, and may be delayed or fail. Privacy policy: https://schwarz-wurm.dev/sensorphone/datenschutz.html