MooTools is an open source JavaScript framework that evolved from the simple function called moo.fx. The developers of moo.fx have slowly expanded this simple function into a fully functional framework. As of this writing, the framework is on its 1.2.0 version and has been enjoying a good following along with other JavaScript frameworks. MooTools is a lightweight framework. But do not think MooTools is another lightweight framework that would eventually stack-up. This framework is as lean as they could be. Instead of stacking up the functions and lines, MooTools divide the codes by developing functions in small code bases.