Cloud Services for Synchronization and Sharing (CS3) [14] have become increasing popular in the European Education and Research landscape in the last years. Services such as CERNBox, SWITCHdrive, SURFdrive, PSNCBox, Sciebo, CloudStor and many more have become indispensable in everyday work for scientists, engineers, educators and other users in public research and education sector. CS3 services are currently too fragmented and lack interoperability. To fix this problem and interconnect storage-, applicationand research services a set of interoperable interfaces, CS3APIs [10], has been developed. CS3APIs enable creation of easily-accessible and integrated science environments, facilitating cross-institutional research activities and avoiding fragmented silos based on ad-hoc solutions. In this paper we introduce the CS3APIs and its reference implementation, Reva [16].