Play

Play is a web framework for building applications in Scala and Java. Guillaume Bort created it at Zenexity (now Zengularity) and open-sourced it in 2009. Unlike traditional Java servlet-based frameworks, Play uses a fully non-blocking, stateless architecture — requests never tie up a thread waiting for I/O, which keeps resource consumption predictable under load.

The current release is Play 3.0, which replaced Akka with Apache Pekko as its concurrency runtime after Lightbend changed Akka's license. Play supports both Scala 3 and Java, with hot-reload during development and a built-in test framework. In 2021, Lightbend handed stewardship to an independent community organization that now maintains the project.

The official documentation covers both the Scala and Java APIs. The source code is on GitHub under the Apache 2.0 license.