What is GPL? Understanding the License Behind WordPress Themes and Plugins

Last Updated: March 11, 2025

If you've spent any time in the WordPress ecosystem, you've likely encountered the term "GPL" or "GPL-licensed" when browsing themes and plugins. But what exactly is GPL, why does it matter for WordPress users, and how does it impact the themes and plugins you use on your website?

In this comprehensive guide, we'll demystify the GNU General Public License (GPL), explain its significance in the WordPress community, and help you understand the practical benefits and implications for website owners, developers, and businesses.

What is the GPL (GNU General Public License)?

The GNU General Public License, commonly known as GPL, is a free, copyleft license for software and other creative works. Created by Richard Stallman in 1989 (and since updated through several versions), the GPL was designed to guarantee users the freedom to run, study, share, and modify software.

At its core, the GPL is built on four essential freedoms:

1. The freedom to use the software for any purpose
2. The freedom to study how the program works and adapt it to your needs
3. The freedom to redistribute copies to help others
4. The freedom to improve the software and release your improvements to the public

Key Characteristics of GPL

• Copyleft: Unlike permissive licenses, GPL requires that any derivative works also be distributed under the same license terms
• Inheritance: When GPL code is incorporated into another project, the entire project must be GPL-compatible
• Source Code Access: GPL requires that source code must be made available when distributing the software
• No Additional Restrictions: Distributors cannot add restrictions beyond what the GPL allows

WordPress and GPL: A Foundational Relationship

WordPress itself is released under the GPLv2 (or later) license. This licensing choice by WordPress founder Matt Mullenweg was instrumental in fostering the massive ecosystem we see today.

Why WordPress Chose GPL

The decision to license WordPress under GPL was strategic and philosophical:

1. Community Focus: GPL aligns with WordPress's community-driven development model
2. Democratizing Publishing: GPL supports WordPress's mission to make publishing accessible to everyone
3. Collaborative Innovation: GPL enables developers worldwide to contribute improvements
4. Long-term Sustainability: GPL ensures WordPress remains free and open regardless of who maintains it

Matt Mullenweg has frequently emphasized that GPL is not just a technical choice but the ethical foundation of WordPress, describing it as the "bill of rights" for WordPress users.

WordPress Themes and Plugins Under GPL

Since WordPress is GPL-licensed, there are important implications for themes and plugins:

The GPL Inheritance for WordPress Extensions

WordPress themes and plugins are considered derivative works of WordPress because:

1. They incorporate WordPress code: Themes and plugins use WordPress functions, hooks, and APIs
2. They're designed to work within the WordPress ecosystem: They're specifically created to extend WordPress functionality
3. They depend on WordPress to function: They cannot operate as standalone software

Because of this, according to the Free Software Foundation and the WordPress Foundation, WordPress themes and plugins must be GPL-compatible (at least the PHP portions).

The "Split License" Debate

There has been some debate about whether certain components of themes (like CSS, JavaScript, and images) can be licensed separately from the PHP code. This led to the concept of "split licensing," where:

• PHP code is released under GPL (as required)
• Assets like images, CSS, and JavaScript might use a different license

However, the WordPress Foundation's official position is that the entire theme should be GPL-licensed, and this has become the standard for the official WordPress theme and plugin repositories.

Practical Implications of GPL for Website Owners

As a website owner using WordPress, understanding GPL has several practical implications:

What You CAN Do with GPL Themes and Plugins

1. Use on Multiple Sites: You can install GPL themes and plugins on as many websites as you want, including client sites
2. Modify the Code: You can customize and adapt themes and plugins to suit your specific needs
3. Share with Others: You can give copies to friends, colleagues, or clients
4. Distribute Modified Versions: You can share your customized versions (under GPL)
5. Sell GPL Products: You can sell GPL themes and plugins, even if you weren't the original creator

What You CANNOT Do with GPL Themes and Plugins

1. Restrict Others' Freedoms: You cannot prevent others from exercising the same freedoms you enjoy
2. Change the License: You cannot remove the GPL license from the software
3. Add Restrictive Terms: You cannot add terms that contradict the GPL (like prohibiting redistribution)
4. Claim Ownership of Others' Code: You cannot claim copyright on code you didn't create

Common Misconceptions About GPL

Several misconceptions about GPL persist in the WordPress community:

Misconception 1: "GPL means everything is free of charge"

Reality: GPL concerns freedom of use and modification, not price. Developers can and do charge for GPL software.

Misconception 2: "Using a GPL theme means my content is GPL"

Reality: The GPL applies to the theme code, not to your content. Your articles, images, and data remain under whatever copyright you choose.

Misconception 3: "GPL software has no copyright"

Reality: GPL software is copyrighted. The license grants specific permissions while retaining copyright protection.

Misconception 4: "Anyone can take my GPL product and sell it"

Reality: While true technically, this overlooks the value of original authorship, support, updates, and brand trust.

The Business Model of GPL WordPress Products

If anyone can legally redistribute GPL code, how do businesses selling WordPress themes and plugins survive? Several successful business models have emerged:

1. Support and Services

Many successful WordPress businesses focus on exceptional support, documentation, and services rather than just the software itself.

2. Regular Updates

Staying current with WordPress core, security best practices, and new features provides ongoing value that customers are willing to pay for.

3. Community and Ecosystem

Building a community around products creates value beyond the code—through extensions, add-ons, and learning resources.

4. Premium Features and Extensions

Some businesses offer a core GPL product with premium extensions or feature upgrades available for purchase.

5. Software as a Service (SaaS)

Some WordPress products operate on a SaaS model, where the service itself (not just the code) is what customers pay to access.

GPL vs. Other Software Licenses

To better understand GPL, it's helpful to compare it with other common software licenses:

GPL vs. MIT License

• MIT: Very permissive; allows code to be used in proprietary software
• GPL: Requires derivative works to also be GPL; prevents code from becoming proprietary

GPL vs. Creative Commons

• Creative Commons: Designed primarily for creative works like text, images, and media
• GPL: Specifically designed for software and source code

GPL vs. Commercial/Proprietary Licenses

• Commercial/Proprietary: Restricts copying, modification, and redistribution
• GPL: Guarantees these freedoms while ensuring derivatives remain free

How to Verify if a WordPress Theme or Plugin is GPL-Compliant

When purchasing themes or plugins, you might want to verify they're properly GPL-licensed. Here's how:

1. Check the License Information

Look for explicit license information in:

• The product's readme.txt file
• The header of PHP files
• The product's documentation or website

2. Look for License Terms

Legitimate GPL products should:

• Mention GPL version (usually GPLv2 or later)
• Not restrict usage to a specific number of sites
• Not prohibit redistribution or modification

3. Verify Code Accessibility

GPL requires that when software is distributed, the source code must be made available. The code shouldn't be encrypted, obfuscated, or inaccessible.

4. Beware of Conflicting Terms

Some sellers may claim GPL compliance while adding contradictory terms in their user agreements. These terms are not enforceable under GPL but indicate a misunderstanding of the license.

The Benefits of Choosing GPL WordPress Themes and Plugins

At VirusFreeGPL.com, we're committed to offering 100% GPL-compliant themes and plugins. Here's why we believe GPL products are the best choice for WordPress users:

1. Freedom and Flexibility

GPL gives you complete freedom to use and modify your themes and plugins without artificial restrictions.

2. Future-Proofing

If a developer discontinues a product, the GPL ensures you can still use, modify, and update the code yourself or hire someone to do so.

3. Community Support

GPL fosters community contributions and improvements, often leading to better, more secure, and more feature-rich software.

4. Ethical Alignment

Using GPL products aligns with the WordPress philosophy and supports the open-source ecosystem that makes WordPress possible.

5. Legal Clarity

GPL provides a clear, legally tested framework for software use, avoiding ambiguous terms or restrictive conditions.

Common Questions About GPL and WordPress

Q: If I purchase a GPL theme, do I own it?

A: You don't "own" the theme in terms of copyright, but you have the legal right to use, modify, and redistribute it under the terms of the GPL.

Q: Can I use GPL themes on client websites?

A: Yes, you can use GPL themes on any number of websites, including client sites, without additional licensing fees.

Q: Do I need to make my website open source if I use GPL themes?

A: No. The GPL applies to the theme code, not to your website content or business operations.

Q: If I modify a GPL theme, do I need to share my modifications?

A: You're only obligated to share your modifications if you distribute the modified theme to others. Changes for your personal use don't need to be shared.

Q: Can premium themes be GPL?

A: Absolutely. GPL refers to usage rights, not price. Many premium, high-quality themes are fully GPL-compliant.

Q: What's the difference between GPL and GPL-compatible?

A: GPL-compatible means a license works with GPL but might have different terms. For WordPress extensions, being GPL-compatible usually means the code can be integrated with WordPress without license conflicts.

Conclusion: Embracing the WordPress Spirit with GPL

The GPL license is more than just a legal document—it's the philosophical foundation that has enabled WordPress to grow into the world's most popular website platform. By understanding and embracing GPL, you're participating in a community that values freedom, collaboration, and accessibility.

At VirusFreeGPL.com, we're proud to offer a wide selection of premium, 100% GPL-compliant themes and plugins that give you all the freedoms and benefits that GPL provides. Our products combine the quality and support you expect from premium software with the freedom and flexibility guaranteed by the GPL.

Whether you're building a personal blog, a business website, or client projects, choosing GPL themes and plugins ensures you have the freedom to create without artificial limitations.

Ready to explore our collection of GPL WordPress themes and plugins? Visit VirusFreeGPL.com today and experience the perfect combination of premium quality and open-source freedom.

Additional Resources

• GNU General Public License (Version 2)
• WordPress.org's License Page
• Free Software Foundation
• Understanding the GPL by Matt Mullenweg

This article is provided for informational purposes only and does not constitute legal advice. For specific legal questions about GPL or other software licenses, please consult with a qualified legal professional.