Ext

The GNU General Public License(GPL) is the most widely used free and open source software (FOSS) license in the world. The GPL was created and sponsored by the Free Software Foundation (FSF).
http://www.gnu.org/licenses/gpl.html

Prior to Ext 2.1 Ext JS was licensed under a mixed set of licenses. The library itself was licensed under the Ext License, a custom license which granted usage under LGPL terms provided certain conditions were met. The CSS and images "Assets" required to make Ext function were under a proprietary license that prevented derivative works and could not be used without their related Ext JS JavaScript component. This proprietary license created unknown licensing issues - as any modifications made to Ext Components created a derivative work and voided the license for Assets.

We received quite a bit of feedback from the Open Source community about our license being incompatible and not truly open source and we felt the need to address it.

We considered once again releasing under straight LGPL but it was not an option as a business. We tried that with version 1.0 and found out quickly that it enabled others (e.g. large commercial entities) to take our work, wrap it up and sell it as their own. With no mention of us at all. We, as a business with a full time team of talented developers, can not exist under those circumstances. We would quickly become diluted and competing with ourselves.

In the end, we were faced with an identity decision - are we an open source company funded by commercial endeavors or a commercial company with a proprietary framework under a shared source license? Since we started we have been open source and that is the route we will continue on. We chose the GPL specifically because it is the most widely used open source license in the world and yet still afforded us the ability to grow as a company with support through commercial licensing of our products for closed source endeavors.

The GPL is the most widely used open source license in the world. By licensing under GPLv3 we ensure the highest amount of availability in the open source community while still affording us the ability to grow as a company with support through commercial licensing for closed source endeavors.

Ext JS and Ext GWT are both available under GPL v3.

More information about what the GPL license allows is available in the GPL license, Quick Guide to the GPLv3 and official GPL FAQ.

You can download the code base, install it, and modify it as needed. If you modify the code, we encourage you to contribute it back to the Ext community by contributing your modifications under GPL v3 in the Ext forums. Additional information is available in the official GPL FAQ.

Please note that if you distribute your modifications, you will have obligations under the GPL v3.

The simple rule to follow is if you modify any functionality or file in an Ext product for a purpose other than configuration, you have created a modification. All modifications naturally are covered by the GPL v3 license. Additional information is available in the official GPL FAQ.

The following are examples of modifications:

• * Modify Ext JavaScript, Java or CSS source file
• * Extend Ext class or override any Ext functions or methods
• * Modifying an Ext API

The following are not modifications:

• * Creating a new theme in a new CSS file
• * Creating or applying a locale/language pack
• * Overriding property defaults on class prototypes (configuration)

A list of compatible licenses is available on gnu.org.
http://www.gnu.org/philosophy/license-list.html

This compatiblity list includes licenses with can be included in a GPL'ed work. The diagram below shows the directions of compatibility for some common licenses:

More information about the GPL v3 license is available in the official GPL v3 license, Quick Guide to the GPLv3 and official GPL FAQ.