wro4j is a project that will help you to easily improve your Web application page loading time. It can help you to keep your static resources (JavaScript and CSS) well organized, merge and minify them at run-time (using a simple filter) or build-time (using a Maven plugin), and has several features you may find useful when dealing with Web resources.

This release contains about 35 new features, improvements, and bugfixes. The most notable changes include webjar integration and the ability to easily upgrade processors using the webjar dependency only, the latest versions of JSHint and other third party libraries (Ember, Handlebars), the latest version of rhino (unofficial release), and the removal of deprecated methods and classes

wro4j – Freecode