Google core libraries for Java

Distributed and fault-tolerant realtime computation: stream processing, continuous computation, distributed RPC, and more

Asynchronous socket, http(s) (client+server) and websocket library for android. Based on nio, not threads.

Apache Pinot - A realtime distributed OLAP datastore

Distributed Graph Database

Java Indexed Record Chronicle

Utilities for processing user-agent strings. Can be used to handle http requests in real-time or to analyze log files.

Utilities for latency measurement and reporting

a java statsd client library

A stream-based data processor in Java