The useful version of this idea is narrow: a spare Android phone on a charger, pointed at your own front door, your own workshop or your own dog. A free app turns a drawer phone into a workable indoor camera with nothing to buy. It will not match even a cheap dedicated camera on night vision, weather sealing or unattended reliability, and pointing it at other people is a different question with a different answer.
The comparison worth making is the phone against a basic indoor Wi-Fi camera at roughly 25 to 50 dollars, built for constant use. The phone costs nothing.
So a phone suits an indoor, temporary or low stakes watch: a hallway while you are out, a pet, the door where parcels land. Anything permanent outdoors wants a real camera.
Safe ground is your own property and your own space. The word spy is marketing; the job underneath is watching your own hallway. Recording other people covertly is a different act, and in many English speaking jurisdictions a criminal one.
Monitoring a partner or an employee is not what this is for. If the real question is a child's phone, the best parental controls apps for Android cover it. Rules vary by country and by state.
Nearly every app here has the same shape: the old phone becomes the camera, your current phone the viewer, and one account links them, usually by scanning a QR code.
These pair two phones through the developer's servers, which is the quickest setup and puts your video on somebody else's infrastructure. Listings verified in August 2026.
If the point was avoiding a subscription, these keep footage on your own kit.
IP Webcam needs a precaution: set the password the app offers and keep the stream off the public internet, which is how phone cameras end up in public webcam indexes. More in security and privacy.
Dormi by sleekbit is a baby monitor rather than a security camera, and the cleanest here on privacy. Rated 4.0 from about 17,100 ratings, over 1 million installs, updated on 2 June 2026, in-app purchases and no ads. The listing states end to end encryption, no tracking SDKs and nothing stored in the cloud.
It lists WiFi Direct and a hotspot among its connection routes, so it works with no internet at all, plus a connection loss alarm. Four hours a month are free, then a subscription or a lifetime purchase.
Phone motion detection reads changes in the video frame, not heat, so it cannot tell what a person is. A curtain over a radiator, headlights on a ceiling, a cat, the sun coming out: all motion. Sensitivity set too high buries you in alerts, you stop reading them, and the camera becomes decoration.
A phone streaming video runs its camera, its encoder and its radio continuously. Held at full charge in a warm spot an old cell ages faster, and a swollen battery in an unattended phone is a real fire risk. Check the pack first: checking battery health on Android.
Storage is the second wall. Video is large, so local recording fills a 32GB phone quickly, and retention is set per app, so find that setting before you rely on the footage being there. If the device is tight already, see freeing up storage space on Android. Cloud plans solve it with money; check on the app's own pricing screen what the free tier keeps, and for how long.
Night is the third. None of these adds infrared, whatever low light mode is advertised, so a dark room stays dark. Leave a lamp on, or buy the camera. A phone that photographs better than it monitors has a happier use: the best camera apps for Android.
Indoors and in daylight, largely yes: a live view, motion alerts and recording for nothing. Outdoors, in the dark, or as a device you never think about again, no.
Watching your own home, property or pet is normal use. Covertly recording other people is a different matter, and in many places a criminal offence, especially in a bathroom or a bedroom. Audio is regulated more strictly than video.
For monitor style apps such as AlfredCamera, Visory and Security Camera CZ, yes: one phone is the camera, one is the viewer. IP Webcam is the exception, serving a stream you open in a browser or VLC, so one phone and a computer will do.
Recording to the phone itself needs no connection, and IP Webcam states it streams inside a local network with no internet. Remote viewing needs a route in, usually mobile data. Dormi lists WiFi Direct and a hotspot, so two phones can pair with no network.
Use a long, unique password, turn on two factor authentication, and never leave a default in place. With IP Webcam, also keep the stream off the public internet: open camera servers get indexed by strangers.