You may have heard of the GPL (often referred to as WordPress’ ‘Bill of Rights’), but chances are that you don’t fully understand it. And with good reason—it’s a complex topic to tackle, and your time is no doubt better spent making a living than studying product licensing.
However, if you use WordPress, the GPL should matter to you, and you should understand it. Why? Because the GPL defines how WordPress is utilized—by users and developers alike.
With the above in mind, this concise guide will reveal everything that you need to know about GPL licensing as it relates to WordPress, with not a single reference to legalese or unnecessarily complex language. Once you’re finished reading, you will know what the GPL is, why WordPress is licensed accordingly, how the GPL benefits both end users and WordPress developers, and ultimately, why WordPress ‘derivative’ works (i.e. themes and plugins) should (if not must) be licensed under the GPL.
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The GNU General Public License (hereinafter referred to as ‘the GPL’) was created by computer programmer Richard Stallman as a rebellious reaction to the enormous growth of proprietary software. It was named the ‘GNU’ GPL, as it was initially used by Stallman to license the GNU operating system.
The GPL is a ‘free software’ license. Contrary to popular understanding, the use of the word ‘free’ within ‘free software’ refers not to price, but (by Stallman’s definition) to the user’s freedom to utilize, modify and distribute the software (and any ‘derivative’ works).
The GPL is best summarized by the four ‘freedoms’ associated with the ‘free software’ movement:
In other words, the GPL is the antithesis to proprietary software—the likes of Windows or iOS. It empowers the end user and doesn’t necessarily work in the best interests of the developer.
However, as we will discover, it certainly does work for WordPress developers (if not perhaps by design).
WordPress is what it is because of the GPL. The world’s most popular content management system has benefitted from the input of literally thousands of people, from its inception and through to present day, in such a way that simply isn’t possible with proprietary software.
In fact, WordPress never would have existed without the concept of ‘free software’—it was originally a ‘fork’ of b2/cafelog, which was ‘free software’ itself.
The co-founder of WordPress, Matt Mullenweg, is arguably one of the world’s leading voices on ‘free software’. He established WordPress.com with clear mission: to “democratize publishing”. The tenets of GPL mean a great deal to him (as you will discover).
As an end user, there’s a lot to like about the GPL from an ‘ethical’ standpoint. You only need to read Stallman’s impassioned prose on the subject of software ‘ownership’ to understand just how empowering the GPL is for software users:
[Proprietary software] meant that the first step in using a computer was to promise not to help your neighbor. A cooperating community was forbidden. The rule made by the owners of proprietary software was, "If you share with your neighbor, you are a pirate. If you want any changes, beg us to make them."
The idea that the proprietary software social system—the system that says you are not allowed to share or change software—is antisocial, that it is unethical, that it is simply wrong, may come as a surprise to some readers. But what else could we say about a system based on dividing the public and keeping users helpless?
In a world that is becoming increasingly ‘accessible’ (for better or worse), the GPL stands for true transparency in software development.
It’s not just transparency that makes the GPL so powerful. Chris Lema put it best in his article on GPL WordPress themes and plugins:
One might reasonably argue that WordPress’ GPL licensing has been a primary catalyst of its exponential growth. The size of its community, along with its popularity, is unparalleled. It has its GPL status to thank for that.
From a more practical perspective, the GPL gives WordPress end users peace of mind. Not only is WordPress ‘free’ (in both senses of the word), but all trademarks relating to WordPress are owned by the WordPress Foundation — a charitable organization formed with the sole aim of “ensur[ing] free access, in perpetuity, to the software projects we support”. In other words, WordPress always has, and always will be, freely available to us in all of the ways we are used to.
There’s no reason to dislike the GPL from an end user’s point of view. It’s gloriously empowering.
However, the main reason your typical WordPress entrepreneur might have a negative knee-jerk reaction to a fuller understanding of the GPL is what it means from a commercial point of view. After all, if the GPL affords the “freedom to utilize, modify and distribute the software (and any ‘derivative’ works)”, what does that mean for premium themes and plugins, which one might reasonably assume to be ‘derivative’ of WordPress?
In theory, WordPress’ GPL licensing means two things for those who seek to create ‘derivative’ products:
However, it’s not that simple. In reality, the GPL ‘works’ for WordPress developers too.
But before we get onto that, let’s the GPL’s power from a legal perspective. As of this writing, GPL licensing is largely unproven in the courts. In practical terms, that means two things:
It’s not crystal clear whether themes and plugins are legally considered ‘derivative’ works (which would determine whether or not they should be GPL compliant).
However, you’ll find plenty of people ready and willing to disagree with that assertion. Mullenweg went so far as to consult the Software Freedom Law Center for their legal opinion.
Their conclusion (as summarized by Mullenweg) seems absolute: “PHP in WordPress themes must be GPL, artwork and CSS may be but are not required.”
Tomaž Zaman adopts an equally strong point of view in his Codeable article on WordPress and the GPL:
It all seems rather compelling, but most importantly, none of this has been proven in a court of law. There is no legal precedent, and as such, any claim to certainty cannot in fact be certain. Legal certainty is attained through legal precedent—something that the GPL license lacks when it comes to this particular topic.
One could argue that a lack of legal precedence demonstrates that non-compliance is unlikely to result in legal action. Brian Krogsgard explains it well:
While it’s easy to argue the above, to put yourself in the line of fire (so to speak) is something else altogether! We personally wouldn’t advise you to flout the GPL on the assumption that a lack of legal precedence is some sort of ‘protection.’
All this leads to a simple conclusion: Legally speaking, the jury is (quite literally) still out on the GPL’s influence on WordPress themes and plugins.
Having said that, while it’s important to mention the legal aspects of the GPL, that’s not what matters truly from a practical point of view.
As a WordPress entrepreneur, it’s easy to fear what the GPL might mean for your business, but there’s far more value in observing its effects in reality.
History has demonstrated that the WordPress community simply doesn’t work as a cynic might expect it to, for three key reasons:
All of the above means that as a developer, you benefit from all of the good things about the GPL (ethical do-goodery, community spirit and power), but don’t suffer any potentially feared negative side effects.
Then there’s the even better news for client-facing WordPress developers: the GPL doesn’t affect non-distributed work—which includes custom work that you do for a single client. If you’re doing this kind of work, you don’t have to worry about GPL compliance.
While the majority of WordPress users haven’t even heard of the GPL, it is extremely important to all of the key influencers within the WordPress community—the best example being none other than Matt Mullenweg, the co-founder of WordPress and the CEO of Automattic.
He is truly passionate about GPL and is not afraid to protect it accordingly. Examples abound, most recently (and publicly) with the Automattic vs. Thesis saga.
By adopting the GPL license, you are adopting the same ethical and philosophical standpoint as some of the most important people within the WordPress community. Since WordPress is all about community, one would consider doing so a wise move.
The WordPress.org theme and plugin repositories are extraordinary resources for end users, and extraordinary marketing tools for developers. Any developer has the opportunity to upload their themes and/or plugins at no cost and have them exposed to the WordPress community. There’s just one catch: “Your plugin [or theme] must be compatible with the GNU General Public License v2, or any later version.”
Quite simply, when it comes to free theme and plugin developers: no GPL, no exposure on WordPress.org.
GPL licensing can be thought of from a more practical perspective: Without WordPress, your plugin or theme wouldn’t exist, nor would it be able to take advantage of such a huge platform for adaption and exposure. Therefore, while adopting the GPL isn’t unquestionably necessary, all other things being equal, it’s the ‘right’ thing to do.
Now you know everything you need to know about WordPress and the GPL. You understand why it is important to you as an end user, and you understand how ultimately it benefits you to adopt it as a developer.
One might reasonably argue that the only way that the GPL could damage you is if you refuse to adopt it; not because of the licensing itself, but because of the limitations it places on you, the fallout within the community, and the enemies you may attract.
That aside, there’s a lot to love about the GPL from an ethical point of view. WordPress’ chosen license demonstrates that it is possible to create and distribute software in an entirely transparent fashion, while reaping the benefits of community, and making some money along the way. Isn’t that a win for everyone?