For current stable release (2.5.1) check the documentation page.

Snapshots

Snapshots of the latest development version of Akka docs are available

Documentation: Java Manual Java API Scala Manual Scala API

Archive

Akka 2.4.18

Akka 2.4 was the previous stable version. Unsupported, only patched if critical bugs are found.

Documentation: Java Manual Java API Scala Manual Scala API

Artifacts are available from maven central.

Akka 2.3

Akka 2.3 reached end-of-life April, 2017 with the last version being 2.3.16.

Documentation: Java Manual Java API Scala Manual Scala API

Artifacts are available from maven central.

Older versions of Akka

Even older release are available from maven central for their respective version number.