JLicense is a Java utility library for creating and validating license keys. AuthToken is Java utility library for generating and validating authentication tokens (i.e., an encrypt string). [Freeware, pay for sources]

Consists of four Java components that provide streaming HTML-to-PDF conversion, streaming ZIP file generation, HTTP file uploading, and emailing.

A business rule engine class library.

Collection of open source reusable Java components from the Apache/Jakarta community.

Implementation of the JSR-107 JCache API. Its aim is to provide an open source alternative to commercial jcache implementations and deliver a fast distributed caching mechanism for java and j2ee. [Open source, LGPL]

Utility classes for the java collections framework. [Open source, GPL or LGPL]

Class libraries that extend JDK libraries, providing many commonly-used algorithms and data structures. By Recursion Software, Inc. [Commercial]

A general-purpose plug-in framework intended to help building scalable, extendable Java applications with low cost of maintenance. [Open source, LGPL]

This library adds a higher layer of abstraction to the standard Java print API. It has an opened architecture and simplifies the printing of complex components (e.g. tables) and reports. An interactive print preview is also included.

Java class library. The main objective is to provide a cross platform, multi-language set of utilities for use with Java applications.