In celebration of the 10th anniversary, Scala Days in 2019 took place where it all started - at EPFL in the SwissTech Convention Center. The Scala Days conference started in 2010, with about 150 people. In the meantime, it grew to become the leading Scala conference in the world, with two editions every year, around 1500 participants, great workshops, related community events; attracting businesses, developers and Scala lovers all over the globe. For 10 years, Scala Days have brought together developers to share their experiences and new ideas around creating applications with Scala and related technologies, like Spark, Kafka, and Akka. Scala Days provides a unique opportunity for Scala users to interact with the contributors to the language and related technologies and connect with fellow developers.