MapDB provides concurrent Maps, Sets and Queues backed by disk storage or off-heap-memory. It is a fast and easy to use embedded Java database engine.

Fluent testing assertions for Java and the JVM

TwelveMonkeys ImageIO: Additional plug-ins and extensions for Java's ImageIO

Elegant parsing in Java and Scala - lightweight, easy-to-use, powerful.

NoSQL embedded document store for Java

Official MiG Layout for Swing, SWT and JavaFX

IzPack - Source Code

Rembulan, an implementation of Lua 5.3 for the Java Virtual Machine

Template engine for natural languages that allows using grammatically appropriate word forms

BuildNumber Maven Plugin

Combine and minimize JavaScript with Closure Compiler.