7. Apache Kafka

Average annual salary in 2016: $122,728

Year-over-year change: New skill

Apache Kafka is an open-source, distributed streaming platform that helps build real-time data pipelines and streaming apps, according to the Apache Software Foundation. The platform allows one to publish and subscribe to streams of records, similar to a message queue or enterprise messaging system; allows one to store streams of records in a fault-tolerant way; and process those records as they occur, the foundation says.