It sounds a bit Big Brother, I know, but using tech to keep an eye on people you care about and where they are can be a good thing. There are several different kinds of circumstances where it might be useful. You might want to know where your children are so you can be assured they are safe or simply know how to get to them if you need to.
Or you might want to know where business colleagues are if you are out and about as a group doing some work task or other. The developers of Folr even suggest it can be used in educational organisations to keep track of students.
With Folr installed you decide who you want to follow from your contact list, and the app then sends the person a request. If they are happy to be followed, they download the app, and Bob's your uncle.
For Folr to work well the person being tracked needs to play ball. They can deactivate Folr for set times so they can't be followed, making this very much an opt-in service.
OS: Android, iOS