Family Tracker lets you keep up on everybody’s whereabouts “without a flurry of calls.” Once members of your group accept an invitation to your network, the app uses the GPS in their smartphones to track their locations. ($6 for iOS, $5 for Android)
GPS Tracking Pro is a free app that does the same kind of tracking, but only in a limited area. (Android only)
Find My Friends sends out a request to your contacts’ phones each time you want to know where they are. If they accept, you’ll see them on a map. (Free, iOS only)
Find My Kids—Footprints can update a GPS map of your friends or family every time any of them changes location. It will also notify you if one of them enters a spot—like the hotel pool—where you don’t want them wandering unattended. ($2 and up; iOS only)
Source: The New York Times