This document evaluates AppScale, an open-source platform that allows Google App Engine applications to run on distributed data stores like HBase, Cassandra, and MongoDB. It describes AppScale's features for porting applications between data stores and compares the performance of different data stores under light, medium, and heavy loads. While AppScale provides access to many data stores, each varies in how fully it implements the App Engine APIs. The document calls for expanding AppScale's services to new domains and integrating additional databases.