It is an unofficial supplement to http://www.joomla.org/content/view/3510/1/
This is my interpretation of the answers based on reading many posts on the various threads. This is not posted on behalf of OSM or the FAQ team. I am not a lawyer; please do not rely on this for legal advice.
Many of these questions and answers are copied from forum posts. Thank you to the people who wrote them. If you object to the inclusion of your work, please inform me.
Am I allowed to sell extensions?
Yes. The only limitation is that these extensions should be licensed under GNU GPL or a compatible license.
What is the difference between commercial and proprietary?
Commercial means that the application is sold in some way. Proprietary, in the case of Joomla!, means that the GNU GPL requirements of open source, modifiability, copying and/or redistribution are not being met.
What is the rider people keep mentioning?
For approximately 11 months there was a rider attached to the pre-release code for Joomla! 1.5. This “rider” would—if it were implemented-- have permitted propriety extensions for Joomla! 1.5. However, this rider was not approved by the Core Team and, perhaps more importantly, the individual copyright holders—the people who contributed the code that makes up Joomla! and the Mambo release that Joomla! is a fork of—were not asked for permission and were not notified of the change. This failure is contrary to the terms of the GNU GPL license.
From the svn logs
The rider was added:
Name: xxxxxxx xxxxxxxxx
Time: Thursday, May 11, 2006 15:53:22 UTC
The rider was removed:
Name: xxxxxxxxx xxxxxxx
Time: Friday, April 13, 2007 22:02:11 UTC
[edited to remove names at the suggestion of Jick http://forum.joomla.org/index.php/topic ... #msg874338]
The rider has never been a part of anything regarding the 1.0 series. This means that EVERY release of Joomla from 1.0.0 all the way through the current SVN version and every version in between. For exhaustive clarity 1.0.0 - 1.0.12+ has NEVER had the rider added to it. It has always been the pure GPL.
The rider was only added to the 1.5 SVN trunk, only for 11 months, and without having gone through due process,
Who are the copyright/license owners of Joomla 1.0.X and 1.5 ?
Open Source Matters has the copyright on the combined entity. The copyright is derivative of the underlying copyrights held by the people who developed the code and is subject to licensing limitations.
Who are the copyright/license owners of 3P extensions that work with Joomla?
The developers of those extensions.
If I contributed code to Mambo or Joomla! am I a copyright holder?
Yes. You own the copyright to your own code. As long as you code is a part of Joomla! your permission will be required to change the license.
Why do people keep saying “consult a lawyer”?
Your own lawyer will act on your behalf and in your interests. He or she will be able to review the specific issues related to your extension. Each extension and each developer will present unique issues.
Is Joomla! changing its license and if so why?
No. The announcement by the core team is that the same license will apply to Joomla! 1.5 as applied to Joomla! 1.0. Some developers desired a change, but such a change is not possible under the GNU GPL without the permission of all copyright holders
Why is this happening now?
The core team wanted the pending release of a 1.5 RC to have a clean and clear license and for the Joomla! community of users and developers to understand that license.
Are commercial extensions allowed under GNU GPL?
Yes. However they must themselves be licensed under GNU GPL or a compatible license.
Is it possible that my extension does not meet the definition of derived work?
Anything is possible; this is why you should consult a lawyer with experience in intellectual property.
If an extension/application is free standing, can I make a URL link to it without it being license under GNU GPL?
Yes. In this case it is not an extension, but is a free standing application.
How can I show that an application is freestanding?
By demonstrating that it is fully operational outside of Joomla!.
What are the disadvantages of re-coding my extension so that it is freestanding?
A free standing extension will not take advantage of the Joomla! API or application framework.
If I write a custom extension for a client does it have to be licensed under GNU GPL?
According to the GNU GPL any derivative work that is distributed must be done so with a GNU GPL compatible license. If you are distributing a custom work, you are still distributing and thus any derivative works must be distributed under a GNU GPL compatible license. Work done under a "work for hire" may be subject to different rights and responsibilities and as such you should consult with an attorney in your jurisdiction. [updated based on comment from ChuckTrukk]
Where can I find out about GNU GPL Compatible licenses?
The Free Software Foundation maintains a list. It may be found at http://www.gnu.org/licenses/license-lis ... reLicenses
If I write a GNU GPL bridge to a non-GNU GPL application, will that meet the Joomla! License requirements?
This will depend on how it is written. You will probably need to consult a lawyer with experience in this area to help you to make this determination.
Will the commercial extensions be taken down from the extensions section of the Joomla site?
Possible changes to the extension site are under discussion and the subject of research. Notice will be given prior to any change.
Isn't it illegal to include proprietary extensions in the Joomla! Extensions Directory
No. The Joomla! Extensions Directory is a listing service, not a distribution service. It does not itself distribute any extensions.
I have written a component, module, or template for Joomla! and released it under the GPL and I charge a fee for it, but web site X is giving it away for free! Is that right?
If someone pays your fee, the GPL also gives him or her the freedom to pass on the software with or without a fee because the GNU GPL license must go along with the distribution of the software. Whether this is right is an ethical and philosophical issue, not a legal one.
If a developer releases a product under GPL, but makes it undocumented, can the separate documentation then be released in a non-GPL manner?
Yes. The documentation does not derive from Joomla!'s GPL code in any way (assuming that documentation is not in the code). You are the author and you hold the copyright.
If I create a custom extension exclusively for my client, must that extension be available for public download?
Why can't the Joomla! 1.5 APIs be licensed under the LGPL?
This use of the LGPL is one of several approaches that continue to be researched for the future. Any change would have to be agreed to by all of the copyright holders. As with any license it creates its own set of issues.
What is fair use?
The U.S. Copyright Office providesinformation on fair use on this page: http://www.copyright.gov/fls/fl102.html and you should review this page and other relevant materials thoroughly, perhaps with professional advice, if you are considering whether a planned use of par of a copyrighted work under fair use.
According to that page,
The distinction between “fair use” and infringement may be unclear and not easily defined. There is no specific number of words, lines, or notes that may safely be taken without permission. Acknowledging the source of the copyrighted material does not substitute for obtaining permission.
What is the difference betweed donations and payments?
Both donations and payments in exchange for software are acceptable under GNU GPL.
Can a user demand my non gpl code?
First, there is never an obligation to distribute your work.
Second, if you do distribute your work under the gpl, you do need to make the source code available to anyone to whom you distribute it.
If you choose to distribute under a non-gpl license because in your opinion the work is not derivative then you make the decision about whether to distribute your source code.
If you choose to distribute under a non-gpl license, it is the copyright holders of the gpl'ed works that make up Joomla! who have standing to challenge your license, not the individual user. If a copyright holder did challenge your license there would then be a process (it could be a legal process or it could be informal) to determine whether you or the copyright holder is correct in your particular case.
For more information about the gpl and how compliance works see http://www.fsf.org/licensing/compliance.
Where can I learn more about the GNU GPL?
The GNU General Public License: http://www.gnu.org/licenses/gpl.html
The GNU GPL Frequently Asked Questions (FAQ): http://www.gnu.org/licenses/gpl-faq.html
The philosophy behind the GNU: http://www.gnu.org/philosophy/
edited for formatting, spelling, grammar and addition of some new questions and answers.