License4J is a pure Java library for creating and validating licenses. The key concept is features of a license. You can easily add any feature to your license file, i.e. name of the product, version, expiry date, number of executable instances, etc.
JavaScript Drop Down Menu is a fully-featured and accessible menu, that provides useable content to all browsers - including screenreaders, search-engines and text-only browsers.
Jep is a Java library for parsing and evaluating mathematical expressions. With this package you can allow your users to enter an arbitrary formula as a string, and instantly evaluate it. Jep supports user defined variables, constants, and functions.