Rock the JVM (rockthejvm.com) is a Romania-based JVM-focused training platform run by Daniel Ciocîrlan — focused entirely on Scala, the broader JVM ecosystem, and the data-engineering / streaming stack built on top of it (Spark, Flink, Kafka). The platform is one of the most authoritative independent sources on Scala and functional programming on the JVM.
The CourseFlix listing carries four Rock the JVM courses: Scala & Functional Programming for Beginners, Cats (the Scala functional-programming library), Spark Streaming with Scala, and Apache Flink. The teaching style is unusually rigorous about the functional-programming fundamentals underneath the framework material.
Material is paid and aimed at engineers picking up Scala or building data-streaming systems on the JVM. For broader content, see CourseFlix's Scala, Java, and Messaging & Streaming category pages.