akka-core

Akka is a platform for building software systems that need to handle many things at once without slowing down or failing when something goes wrong. It has been downloaded over one billion times and has been in active use for more than fifteen years.

The central idea in Akka is the actor model. In traditional software, multiple parts of a program often compete for access to shared data, which can lead to subtle bugs that are hard to reproduce. The actor model sidesteps this by organizing the program into independent units called actors, each with its own state, that communicate purely by sending messages to one another. This removes the need for locks and other low-level coordination mechanisms that are the usual source of concurrency bugs.

This repository is the Akka core library, which provides the foundational building blocks. On top of it, the Akka SDK lets developers build services that are automatically clustered across multiple machines without writing networking or distribution code by hand. A separately sold managed product called Akka Automated Operations handles deployment, scaling, and multi-region availability within a customer's own cloud environment.

The README lists the kinds of systems people build with Akka: AI inference pipelines, transaction processing, IoT and edge computing, digital twins, and data analytics. It claims the platform can support millions of concurrent users, process terabytes of streaming data, and achieve very high uptime. For fault tolerance, Akka uses what it calls the let-it-crash model, borrowed from the telecom industry: instead of trying to recover from every possible failure, a component that fails is simply restarted by a supervisor.

The core library is licensed under the Business Source License 1.1, which has some restrictions compared to a standard open-source license. Documentation for both the Scala and Java APIs is at doc.akka.io.