Which app alerts you when a friend is near
Quick answer
An app that alerts when a friend is near can work without live sharing: it checks the distance between you and a saved location on your own phone, then sends a local notification.
Most apps that flag a nearby friend rely on constant location sharing, so both people broadcast their position all day. A privacy-first approach flips that. You store a friend's home location on a list only you can see, and your phone runs the distance check by itself. The result is the same useful alert, minus the surveillance. Battery holds up too, because there is no background streaming to a server.
In one sentence
Parages pings you when you pass near a friend. It tracks nobody.