qooxdoo is dual-licensed under the GNU Lesser General Public License (LGPL) and the Eclipse Public License (EPL). As a recipient of qooxdoo, you may choose which license to receive the code under.

The above holds for any newer qooxdoo release. Only legacy versions 0.6.4 and below were licensed solely under the GNU Lesser General Public License (LGPL).

"Ignorance of the law is not an excuse".

For a full understanding of your rights and obligations under these licenses, please see the full text of the LGPL and/or EPL.

One important aspect of both licenses (so called "weak copyleft" licenses) is that if you make any modification or addition to the qooxdoo code itself, you MUST put your modification under the same license, the LGPL or EPL.

Note that it is explicitly NOT NEEDED to put any application under the LGPL or EPL, if that application is just using qooxdoo as intended by the framework (this is where the "weak" part comes into play - contrast this with the GPL, which would only allow using qooxdoo to create an application that is itself governed by the GPL).

Parts of qooxdoo may be available under other licenses that are compatible with the LGPL and the EPL. For instance, source code that is governed by licenses like BSD or MIT, or source code that has been put into the Public Domain by its author can be used within qooxdoo. Files or folders that include such source code, which is under licenses different to qooxdoo's dual license LGPL/EPL, mention those other licenses explicitly.

The following text is from the content of the qooxdoo-specific LICENSE or license.txt file, which for instance can be found in the top-level directory of a regular qooxdoo SDK:

qooxdoo Licensing Information
=============================

qooxdoo may be used under the terms of either the

  * GNU Lesser General Public License (LGPL)
    http://www.gnu.org/licenses/lgpl.html

or the

  * Eclipse Public License (EPL)
    http://www.eclipse.org/org/documents/epl-v10.php

As a recipient of qooxdoo, you may choose which license to receive the code 
under. Certain files or entire directories may not be covered by this 
dual license, but are subject to licenses compatible to both LGPL and EPL.
License exceptions are explicitly declared in all relevant files or in a 
LICENSE file in the relevant directories.

The following is focusing on the LGPL, as it specifically imposes some restrictions on the ability to use other licenses in a "compatible" way. Everybody contributing to the qooxdoo framework must make sure to add code or modify existing code only if the external work used is governed by a license compatible to the LGPL. To help identifying those compatible licenses, you may want to take the following info into account:

• Compatibility of various licenses (according to FSF)
• Compatibility of their own licenses (according to FSF)
• Compatibility of various licenses (according to Wikipedia)
• Open Source Licenses Comparison (according to KDE)

If you want to contribute code or other resources to qooxdoo, which would really be great , we ask you to fill out the following form and send it as an email to
license AT qooxdoo DOT org. This ensures that we have all substantial contributors clearly state the acceptance of the licensing terms.

The qooxdoo project uses code or other contributions originally 
created by me,  <NAME>

I hereby grant the permission to license these contributions under a dual license of 
LGPL/EPL, where LGPL is the GNU Lesser General Public License and EPL is the 
Eclipse Public License.

I also understand and agree that all future contributions I may make to the qooxdoo 
project must be governed by the same dual license LGPL/EPL to be qualified for 
inclusion into the project. This applies both to direct commits to the source code 
repository as well as to any other means that allow me to contribute code or other 
resources.

I understand the rights and obligations that are associated with these two licenses.

<DATE>

<YOUR NAME>

Note, there are lots of ways for you to help with improving and promoting qooxdoo, so please see how to Get involved and give back to the project!

If you have any questions regarding the rights and obligations that come with qooxdoo's license, even after you carefully acquainted yourself with the licensing terms, please feel free to contact license AT qooxdoo DOT org.