EgiGeoZone Geofence is a useful app for Android with over 10,000 users that allows you set up triggering based on location. There’s also a Bluetooth version that allows triggering in the vincinity of iBeacons.
The app is also open source on GitHub. Note that the app doesn’t yet work with the Android 8.0 background changes. The author is hoping someone else will fork the code and keep the app alive.