MooTools
MooTools (My Object-Oriented Tools) is a lightweight, object-oriented, JavaScript framework. It is released under the free, open-source MIT License. It is used on more than 5% of all websites, and is one of the most popular JavaScript libraries.
GNU General Public License
GNU General Public License
The GNU General Public License (GNU GPL or simply GPL) is the most widely used free software license. It was originally written by Richard Stallman for the GNU Project.
The GPL is the first copyleft license for general use, which means that derived works can only be distributed under the same license terms. Under this philosophy, the GPL grants the recipients of a computer program the rights of the free software definition and uses copyleft to ensure the freedoms are preserved, even when the work is changed or added to. This is in distinction to permissive free software licenses, of which the BSD licenses are the standard examples.