A CMS licence decides what you may do with the code. GPL and MIT let you use, modify and run it commercially without paying a fee, with different conditions on sharing changes. Source-available and commercial licences usually charge per project, and SaaS terms govern a service rather than software you hold.
A licence is the document that says what you may do with a piece of software. For a publisher, it answers practical questions: Can we change the code? Can a developer sell us a customised version? What happens if the vendor changes its pricing? This guide explains the main licence types used by publishing systems and gives real examples. It is general information, not legal advice. For anything contractual, ask a lawyer.
What are the main types of CMS licence?
Most systems fall into one of four groups, and the group tells you more than the product name.
- Copyleft open source (such as the GPL): you can use, change and share the code, but modified versions you distribute must carry the same terms.
- Permissive open source (such as MIT): you can do nearly anything, including building closed-source products, provided you keep the notice.
- Source-available or commercial licences: you may see or modify the code, but use is governed by a paid licence with limits.
- SaaS terms: you do not receive the code at all, only access to a hosted service.
How does the GPL work for a publisher?
The GNU General Public License is the licence behind several of the best-known publishing systems. Drupal says it, and the contributed files derived from it on Drupal.org, are licensed under GPL version 2 or later. WordPress states it is released under GPLv2 or later and that derivatives of WordPress code inherit the GPL. Joomla’s repository says it is distributed under GPL version 2 or later.
Three points matter most in practice. You can sell: the GNU project’s FAQ says the GPL allows everyone to sell copies and that the right to sell is part of the definition of free software. You can keep changes private: the same FAQ says the GPL does not require you to release your modified version, and that you may use modifications privately. And your content is not the software: your articles, photographs and brand are separate from the CMS code.
The obligations arise when you distribute. An agency that hands a client a modified GPL system must pass on the same freedoms, including the source. Running a modified copy on your own server is not distribution in the sense of GPL version 2, which is why a company can customise a CMS for its own site without publishing the changes.
The network clause is different. The GNU Affero GPL, a related licence, requires that modified versions offer users interacting with them over a network an opportunity to receive the source. If a product you are considering uses the Affero licence, check with the vendor what that means for your changes.
What does the MIT licence allow?
The MIT licence is short. It permits use, copying, modification, merging, publishing, distribution, sublicensing and selling of copies, on condition that the copyright and permission notice stay with the software. It provides the software without warranty. That makes it the easiest licence for agencies who want to build proprietary products on top.
Ghost’s repository states it is released under the MIT licence, and Umbraco CMS states the same. Note that a licence on code is separate from a trademark: Ghost’s repository also states that Ghost and the Ghost logo are trademarks of Ghost Foundation Ltd, so you cannot rebrand and pass off your product under that name.
What about open core, source-available and commercial licences?
Some projects mix licences. Strapi’s Community Edition is provided under the MIT Expat licence, but any component under an ee/ directory is the Enterprise Edition and is not licensed under MIT Expat. In practice that means a free core with paid features under separate terms, so check which side of the line a feature you need falls on.
Craft CMS uses its own licence. Its licence file says a licence is required for production use and that each licensed copy may be actively installed in no more than one production environment at a time. The code is visible, but running it commercially means paying per project, which our cost guide covers.
Licence comparison for real CMS examples
| CMS | Licence | What it means for you | Source |
|---|---|---|---|
| Drupal | GNU GPL v2 or later | Free to use, change and sell; distributed changes keep GPL terms | drupal.org licensing page |
| WordPress (software) | GPLv2 or later | Same; plugins and themes derived from its code inherit the GPL | wordpress.org licence page |
| Joomla | GNU GPL v2 or later | Same | Joomla CMS repository |
| Ghost | MIT | Permissive; keep the notice; trademark is separate | Ghost repository |
| Umbraco CMS | MIT | Permissive | Umbraco-CMS repository |
| Strapi | MIT Expat for Community Edition; separate Enterprise licence for ee/ code | Free core; paid features under different terms | Strapi LICENSE file |
| Craft CMS | Craft’s own licence | Paid licence needed per production installation | Craft LICENSE.md |
Licences change. Before relying on this table, open the source linked in each row of the claims on this page and confirm the current text.
What do SaaS terms change?
With a hosted service you rent access. The vendor’s terms, not a software licence, decide what you may do. Look for how your content is exported, whether you can use a custom domain, what happens on cancellation, how price changes are notified and whether the vendor may suspend your site. A SaaS product can be built on open-source code and still limit what you can do with the service.
Questions to ask before you commit
- Does production use need a paid licence, and is it per site, per developer or per user?
- Which features sit behind a separate commercial licence or subscription?
- What licence do the plugins and themes we will use carry?
- If we stop paying, can we keep running what we have?
- Can we export articles, media and redirects in an open format?
The answers feed straight into the feature checklist, and a quick trial will show whether the product behaves the way the sales page says.
Questions people ask
Can I sell a website built on a GPL CMS?
Yes. The GNU project states that the GPL allows everyone to sell copies, and the content you write is yours. The GPL covers the CMS code and, in WordPress's case, derivative code such as plugins and themes, not your articles or images. Check each plugin's own licence as well.
Do I have to publish my changes to a GPL CMS?
Not if you keep them private. The GPL FAQ says you are free to modify the software and use it privately without releasing your version. If you distribute your modified copy to others, they must receive it under the same GPL terms.
Is open source the same as free to run?
No. The licence usually costs nothing, but hosting, development, updates and support still do. Some open-source projects also sell hosting or enterprise add-ons. See the [cost guide](/pricing.php) for the categories involved.
What should I check before choosing a CMS licence-wise?
Read the licence of the core, of any paid add-ons, and of the themes and extensions you plan to use. Check whether production use needs a paid licence, what happens if you stop paying, and whether you can export your content. The [feature checklist](/features.php) includes export and portability.
Is a SaaS CMS covered by an open-source licence?
Usually the service is governed by terms of service rather than a software licence, even if the vendor also publishes open-source code. Your rights to the hosted platform are those in the contract, so read the termination and data-export clauses.
Sources
- Drupal, and all contributed files that are derivative works of Drupal hosted on Drupal.org, are licensed under the GNU General Public License, version 2 or later. — source, checked 10 October 2026.
- WordPress software is released under the GPLv2 (or later) from the Free Software Foundation, and derivatives of WordPress code inherit the GPL licence. — source, checked 10 October 2026.
- The Joomla! CMS repository states it is distributed under the GNU General Public License version 2 or later. — source, checked 10 October 2026.
- Ghost's repository states it is released under the MIT licence (Copyright Ghost Foundation); Ghost and the Ghost logo are trademarks of Ghost Foundation Ltd. — source, checked 10 October 2026.
- Umbraco CMS is described as a free and open source .NET content management system and is licensed under the MIT licence. — source, checked 10 October 2026.
- Strapi's Community Edition is provided under the MIT Expat licence, while any component under an ee/ directory is Enterprise Edition and not licensed under MIT Expat. — source, checked 10 October 2026.
- Craft CMS uses its own licence in which each licensed copy may be actively installed in no more than one production environment at a time, and a licence is required for production use. — source, checked 10 October 2026.
- The MIT licence permits use, copying, modification, merging, publishing, distribution, sublicensing and selling of copies, on condition that the copyright and permission notice are included, and provides the software without warranty. — source, checked 10 October 2026.
- The GNU GPL FAQ states that the GPL allows everyone to sell copies of GPL software and that the right to sell copies is part of the definition of free software. — source, checked 10 October 2026.
- The GNU GPL FAQ states that the GPL does not require you to release your modified version, and that you may make modifications and use them privately without ever releasing them. — source, checked 10 October 2026.
- The GNU GPL FAQ states that a company running a modified version of a GPL-covered program on a website does not have to release the modified sources, because it is not distributing the program. — source, checked 10 October 2026.
- The GNU GPL FAQ states that the GNU Affero GPL requires modified versions to offer all users interacting with them over a computer network an opportunity to receive the source. — source, checked 10 October 2026.