urLocator is an Android app developed by Chia-Hsin Lien that integrates Facebook and Google Maps to allow users to easily track the real-time location of their Facebook friends. To use the app, users need to have a Facebook account and add their friends to the tracking list. However, to successfully track a friend's location, that friend must also have installed the urLocator app.

It's important to note that this is not an official Facebook app and is only available for Android devices running on Android 9.0. For iOS users, a separate version is available for download from the App Store under the name "urLocator-Facebook Edition." Additionally, users must invite their friends to use the app in order to see them connected. Lastly, it's worth mentioning that the program is able to run in the background, so users must explicitly terminate the app to save on battery and network charges.

Overall, urLocator is a useful app for those who want to track the real-time location of their Facebook friends, as long as those friends also have the app installed and running.