RHEEM is a scalable and easy-to-use system for cross-platform big data analytics. It provides an abstraction on top of existing data processing platforms. It allows users to easily specify their data analytics tasks with easy-to-use interfaces, provides developers with opportunities to optimize performance in different ways, and can run on any data processing platform, such as PostgreSQL, Spark, or Hadoop MapReduce. RHEEM abstraction is fully based on user defined functions (UDFs) to allow users to focus on their applications logics rather than on physical details. Users can now implement and deploy their big data analytic tasks on a matter of a couple of days. The salient features of Rheem are cross-platform task execution, high performance, flexibility, and ease-of-use.