GPL
Quick Definition
The GPL (GNU General Public License) is the open-source license WordPress uses. It gives everyone the freedom to use, modify, and distribute the software — and requires that derivative works (themes and plugins) also stay open-source.
What Is the GPL?
The GPL (GNU General Public License) is the open-source license that governs WordPress. It is published by the Free Software Foundation and is the legal foundation that makes WordPress free — not free as in "no cost" (though it is that too), but free as in freedom.
The GPL grants four fundamental freedoms:
- Freedom to use — Run WordPress for any purpose, on any number of sites, with no restrictions
- Freedom to study — Access and read the source code to understand how it works
- Freedom to modify — Change the code to suit your needs
- Freedom to distribute — Share copies of the original or modified code with anyone
WordPress specifically uses GPLv2 (or later). This means you can choose to apply the terms of GPL version 2 or any later version published by the Free Software Foundation.
The GPL's most important provision is copyleft: any work derived from GPL code must also be released under the GPL. This is why every theme and plugin in the WordPress.org directories is required to be 100% GPL-compatible. If you build on WordPress code, your work inherits the same freedoms.
This does not mean developers cannot charge money. Premium themes and plugins are perfectly legal under the GPL — developers sell access to downloads, support, and updates, not the code itself. WooCommerce, Yoast SEO, and every premium plugin on the market operate under the GPL while running successful businesses.
The GPL in Practice
What the GPL means for WordPress users:
- No vendor lock-in — You can switch hosts, hire any developer, and modify anything. No one can take your site away because you stopped paying a license fee.
- Fork freedom — If a plugin developer abandons their project, anyone can fork it (create a new version based on the existing code) and continue development. This has happened many times in WordPress's history.
- Theme/plugin requirement — To be listed in the Theme or Plugin Directory, everything must be GPL. This is non-negotiable.
- "Split licensing" controversy — Some premium themes/plugins release PHP code as GPL (required) but claim CSS, images, and JavaScript are proprietary. WordPress.org does not accept split-licensed themes or plugins, but some developers sell this way outside the directory.
The GPL is why WordPress powers 43% of the web. It ensures that no company — not even Automattic — can make WordPress proprietary. The code belongs to everyone.
Why It Matters
The GPL is not just legal fine print — it is the reason WordPress exists as you know it. It is why you can install any theme, switch any host, and modify any code. It is why 59,000 free plugins exist. And it is why WordPress will remain free and open forever, regardless of what any company does. Understanding the GPL helps you appreciate the ecosystem you are building on — and make informed decisions about the themes and plugins you choose.