https://f-droid.org/packages/com.google.android.gms backend that uses locally acquired WiFi AP data to resolve user location. This backend consists of two parts sharing a common database. One part passively monitors the GPS. If the GPS has acquired and has a good position accuracy, then the WiFi APs detected by the phone are stored. The other part is the actual location provider which uses the database to estimate location when the GPS is not available or has not yet gotten its first fix. The use of stored WiFi AP can dramatically decrease the GPS time to first fix. This backend performs no network data. All data acquired by the phone stays on the phone and no queries are made to a centralized AP location provider.