Scala. Airbnb develops open-source machine-learning software "Aerosolve", written in Java and Scala. Zalando moved its technology stack from Java to Scala and Play. SoundCloud uses Scala for its back-end, employing technologies such as Finagle (micro services), Scalding and Spark (data processing). Databricks uses Scala for the Apache Spark Big Data platform. Morgan Stanley uses Scala extensively in their finance and asset-related projects. There are teams within Google and Alphabet Inc. that use Scala, mostly due to acquisitions such as Firebase and Nest. Walmart Canada uses Scala for their back-end platform. Duolingo uses Scala for their back-end module that generates lessons. HMRC uses Scala for many UK Government tax applications. M1 Finance uses Scala for their back-end platform. Criticism In March 2015, former VP of the Platform Engineering group at Twitter Raffi Krikorian, stated that he would not have chosen Scala in 2011 due to its learning curve. The same month, LinkedIn SVP Kevin Scott stated their decision to "minimize [their] dependence on Scala". In November 2011, Yammer moved away from Scala for reasons that included the learning curve for new team members and incompatibility from one version of the Scala compiler to the next. See also sbt, a widely used build tool for Scala projects Play!, an open-source Web application framework that supports Scala Akka, an open-source toolkit for building concurrent and distributed applications Chisel, an open-source language built on Scala that is used for hardware design and generation. References Further reading Programming languages Articles with example Scala code Concurrent programming languages Free software programmed in Scala Functional languages Java programming language family JVM programming languages Object-oriented programming languages Pattern matching programming languages Programming languages created in 2003 Scripting languages Software using the Apache license Statically typed programming languages 2003 software Cross-platform free software Free compilers and interpreters Source-to-source compilers