Collection Query Engine: NoSQL indexing and query engine for Java collections with ultra-low latency

A framework for testing concurrent Java applications

Kryo is a fast and efficient object graph serialization framework for Java. The goals of the project are speed, efficiency, and an easy to use API.

Very simple java library to generate permutations, combinations and other combinatorial sequences.

Jar Jar Links is a utility that makes it easy to repackage Java libraries and embed them into your own distribution.

ReFit Java EE Example

Is an extremely lightweight efficient Java library to generate XHTML or XML in a micro DSL builder/fluent style.

A library that supports gettext-based internationalization (i18n) of Java applications.

Papaya: Utilities for Java 1.8+ written by Kevin Connor ARPE

charts4j is a free, lightweight charts and graphs Java API. It enables developers to programmatically create the charts available in the Google Chart API through a straightforward and intuitive Java API.