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Build highly concurrent, distributed, and resilient message-driven applications using Java/Scala


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Apache Pekko

Nightly Builds Nightly Aeron Tests OpenSSF Best Practices

Apache Pekko is an open-source framework for building applications that are concurrent, distributed, resilient and elastic. Pekko uses the Actor Model to provide more intuitive high-level abstractions for concurrency. Using these abstractions, Pekko also provides libraries for persistence, streams, HTTP, and more.

Pekko is a fork of Akka 2.6.x, prior to the Akka project's adoption of the Business Source License.

Reference Documentation

See for the documentation including the API docs. The docs for all the Apache Pekko modules can be found there.

Building from Source

The CI build is Linux based (Ubuntu) and most Pekko developers use Macs or Linux machines. There have been reports of issues when building with Windows (#829).


  • Make sure you have installed a Java Development Kit (JDK) version 11 or later.
  • Make sure you have sbt installed and using this JDK.
  • Make sure you also have Java 8 installed (JDK or JRE).
  • Graphviz is needed for the scaladoc generation build task, which is part of the release.

Running the Build

  • Open a command window and change directory to your preferred base directory
  • Use git to clone the repo or download a source release from (and unzip or untar it, as appropriate)
  • Change directory to the directory where you installed the source (you should have a file called build.sbt in this directory)
  • sbt compile compiles the main source for project default version of Scala (2.13)
    • sbt +compile will compile for all supported versions of Scala
  • sbt test will compile the code and run the unit tests
  • sbt testQuick similar to test but when repeated in shell mode will only run failing tests
  • sbt testQuickUntilPassed similar to testQuick but will loop until tests pass.
  • sbt package will build the jars
    • the jars will be built into target dirs of the various modules
    • for the 'actor' module, the jar will be built to actor/target/scala-2.13/
  • sbt publishLocal will push the jars to your local Apache Ivy repository
  • sbt publishM2 will push the jars to your local Apache Maven repository
  • sbt docs/paradox will build the docs (the ones describing the module features)
    • Requires Java 11 minimum
    • sbt docs/paradoxBrowse does the same but will open the docs in your browser when complete
    • the index.html file will appear in target/paradox/site/main/
  • sbt unidoc will build the Javadocs for all the modules and load them to one place (may require Graphviz, see Prerequisites above)
    • the index.html file will appear in target/scala-2.13/unidoc/
  • sbt sourceDistGenerate will generate source release to target/dist/
  • The version number that appears in filenames and docs is derived, by default. The derived version contains the most git commit id or the date/time (if the directory is not under git control).
    • You can set the version number explicitly when running sbt commands
      • eg sbt "set ThisBuild / version := \"1.0.0\"; sourceDistGenerate"
    • Or you can add a file called version.sbt to the same directory that has the build.sbt containing something like
      • ThisBuild / version := "1.0.0"


There are several ways to interact with the Pekko community:

  • GitHub discussions: for questions and general discussion.
  • Pekko dev mailing list: for Pekko development discussions.
  • Pekko users mailing list: for Pekko user discussions.
  • GitHub issues: for bug reports and feature requests. Please search the existing issues before creating new ones. If you are unsure whether you have found a bug, consider asking in GitHub discussions or the mailing list first.


Contributions are very welcome. If you have an idea on how to improve Pekko, don't hesitate to create an issue or submit a pull request.

See for details on the development workflow and how to create your pull request.

Code of Conduct

Apache Pekko is governed by the Apache code of conduct. By participating in this project you agree to abide by its terms.


Apache Pekko is available under the Apache License, version 2.0. See LICENSE file for details.