This chapter discussed two different ways to extend the Google Apps Platform. On one hand there is Google Apps Marketplace where customers can purchase new products. On the other there is Google Apps Engine, which helps design and run application that will benefit from Google's datacenter infrastructure. However, in order to benefit from these high-scalability and high-availability features, a GAE application has to meet a certain number of constraints, among which is the need to use the Datastore, a non-relational persistence mechanism.