Open Source Java Reliable-UDP Libraries

Efficient reliable UDP unicast, UDP multicast, and IPC message transport. Java and C++ clients are available in this repository, and a .NET client is available from a 3rd party. All three clients can exchange messages across machines, or on the same machine via IPC, very efficiently. Message streams can be recorded by the Archive module to persistent storage for later, or real-time, replay. Aeron Cluster provides support for fault-tolerant services as replicated state machines based on the Raft consensus algorithm. Performance is the key focus. A design goal for Aeron is to be the highest throughput with the lowest and most predictable latency of any messaging system. Aeron integrates with Simple Binary Encoding (SBE) for the best possible message encoding and decoding performance. Many of the data structures used in the creation of Aeron have been factored out to the Agrona project.

Agrona provides a library of data structures and utility methods that are a common need when building high-performance applications in Java. Many of these utilities are used in the Aeron efficient reliable UDP unicast, multicast, and IPC message transport and provides high-performance buffer implementations to support the Simple Binary Encoding Message Codec.

An object-oriented implementation of a reliable, in-order, transport protocol over UDP based on the Internet Draft by Bova, Krivoruchka, and Cisco Systems (1999) titled "Reliable UDP".

java-Kcp is a Java implementation of the KCP reliable UDP protocol built on top of Netty. It is designed for applications that need fast, reliable communication over UDP, especially games, video systems, and network acceleration services. The project includes forward error correction support and aims to remain compatible with other KCP implementations, including C, Go, and a related C# version. Its documentation provides server and client examples, usage parameters, best practices, troubleshooting notes, and performance testing information. The library is positioned as stable enough for real projects and has been used in online production scenarios. It is useful for Java backend developers who need low-latency network transport without giving up reliability features.