WordPress Licensing & the GPL
To develop WordPress themes for the public—either free or paid— you need to get acquainted with the GNU General Public License (GPL) that WordPress uses.
GPL basic freedoms
The spirit of openness and sharing has thrived within the WordPress community because of fundamental principles that form the core of its license. One way to think of the GPL is as a “Bill of Rights” for software. The GPL establishes the following four freedoms:
- Freedom to run the program for any purpose.
- Freedom to study how the program works and to change it, so it performs computing as you wish.
- Freedom to redistribute copies, so you can help your neighbor.
- Freedom to distribute copies of your modified versions, giving the community a chance to benefit from your changes.
What is “free” in the context of software?
The ‘free’ in free software, refers to freedom and not price. The Free Software Foundation likes to say “free as in speech, not as in beer.” Free software is software that users can use to do as they wish. It need not be free from cost, although the ones hosted on the WordPress.org theme directory are.
Free software can come with a price tag. In other words, you can create a GPL theme and sell it for $50, and it would still be free software. Why? Because the user is free to run, modify, and distribute the software or any modifications of that software.
Keeping it free for all
The freedoms of the GPL don’t only apply to the original piece of software; works derived from GPL-licensed software must also adopt the same license, without restrictions or additional terms.
In this sense, the GPL provides the ultimate protection of freedom by making sure that anything that is derived from free software cannot be “locked down” after the fact; it must remain forever free to future experimentation and exploration.
Do I need to license my themes under the GPL?
If you have no plans to distribute your theme then you do not need to adopt the GPL license for your work. The GPL only applies to distributed software. If you are not distributing your software – for example, a theme used only by yourself or on your local machine – you do not need to adopt the GPL.
If you wish to submit your creation to the free theme repository on WordPress.org, it must be 100% GPL compliant, including CSS and image files. Because the freedoms spelled out in the GPL are at the heart of WordPress, we encourage developers to distribute their themes with a 100% GPL-compatible license.
Note: Freedom is an important part of developing WordPress themes. If you plan to distribute your theme, it is a good idea to license it fully under the GPL, so others can enjoy the same freedoms that you did when creating it.
To deepen your understanding of WordPress and the GPL:
- WordPress.org: Themes are GPL, too
- Matt: Q&A: WordPress & GPL
- Matt: The Four Freedoms
- GNU General Public License, version 2
- GNU General Public License, version 3