MicroG – free and open source alternative to Android Google services

At this point, several popular open-source applications already require some of Google’s proprietary libraries to be installed. Increasing demand in the free software community in addition to severe problems in Google’s proprietary software discovered by the Android modding community, have led to the development of a free software clone of Google’s proprietary core libraries and applications – the microG Project was born. Service Core (GmsCore) is a library app, providing the functionality required to run apps that use Google Play Services or Google Maps Android API (v2).

Source: microg.org