In the world of free and open-source software (FOSS), licensing plays a crucial role in shaping how software can be used, modified, and shared. While the most common open-source license, the GNU General Public License (GPL), ensures freedom for users, the GNU Affero General Public License v3 (AGPLv3) takes things one step further, especially for software deployed over the network. In this blog post, we’ll explore what the AGPLv3 is, why it matters, and how it addresses the challenges posed by modern software use cases, particularly for web-based applications.
What is the GNU AGPLv3?
The GNU AGPLv3 is a copyleft license designed to ensure that software and its derivatives remain free for everyone, not just in terms of personal use, but also when it’s used for providing services over a network. It is a part of the broader family of GNU licenses, but unlike the standard GPL, which mainly covers software distribution, the AGPL includes a crucial provision for software that is run as a service.
The Big Idea: Network Use is Distribution
One of the defining features of the AGPLv3 is its requirement that source code must be made available when software is used over a network. In practice, this means that if you modify AGPL-licensed software and use it to provide a service—say, hosting a web app or offering a cloud service—you must make the complete source code of your modified version available to any users who interact with it.
In a world where Software as a Service (SaaS) is increasingly popular, the AGPL ensures that companies or individuals who build on open-source projects for network services can’t bypass the open-source principles simply by running the software remotely. For example, if you’re running a modified version of an AGPLv3-licensed app on your web server, you need to make that modified code available to users accessing your service.
Why the AGPLv3 Matters in the Age of SaaS
The rise of cloud computing, APIs, and web-based applications has created a significant shift in how software is used. While traditional open-source licenses like the GPL ensured that users who received a copy of the software could access its source code, the AGPLv3 was created to address a critical loophole: software running on a server. Under traditional licenses, it was easy for companies to take open-source software, modify it, and run it on their servers without ever sharing their changes.
The AGPLv3 prevents this by making network use count as distribution. If a user interacts with your service (even through a web browser), they have the right to request the complete source code of the software you’re running. This ensures that developers don’t get to lock their changes behind a paywall or proprietary platform, maintaining the open nature of the project and ensuring that everyone benefits from improvements and fixes.
Key Features of the AGPLv3
Let’s break down the main features, permissions, and conditions of the AGPLv3:
Permissions
* Commercial Use: You can use, modify, and distribute the software for commercial purposes, including selling services that are built on top of it.
* Distribution: You are free to distribute the original or modified software.
* Modification: You can modify the software, as long as you meet the conditions of the license.
* Patent Use: Contributors to the software grant you a license to use any patents they hold on the software.
* Private Use: You are free to use and modify the software privately, without having to release your modifications unless you choose to distribute them.
Conditions
* Disclose Source: If you distribute the software (or use it to provide a service), you must provide access to the source code, including any modifications you made.
* License and Copyright Notice: The license and copyright notice must accompany the software, whether you're distributing the original or a modified version.
* Same License: If you distribute modified versions of the software, you must also distribute them under the AGPLv3. This ensures that the freedoms provided by the license are preserved.
* State Changes: Any modifications to the software must be documented clearly.
Limitations
* Liability: The AGPLv3 includes a limitation of liability, meaning that the authors are not responsible for any damages caused by using the software.
* Warranty Disclaimer: The software comes with no warranties, meaning that if it doesn’t work as expected, the authors are not liable for fixing it.
The AGPLv3 vs. Other Licenses
The AGPLv3 is often compared to the GPLv3 because they share many characteristics, particularly the requirement to release modified code. However, the key difference is the AGPL's focus on network use. The GPLv3 doesn’t require you to release source code if you’re only running the software on a server and not distributing it, but the AGPL changes this. This makes the AGPL a better fit for modern web applications, APIs, and any service-oriented software.
Another popular license is the MIT License, which is far more permissive and allows proprietary use without any obligations to release source code. The AGPLv3, on the other hand, enforces strong copyleft principles, meaning that it requires you to keep the software open and free for everyone, even if you’re running it in a SaaS context.
When Should You Use the AGPLv3?
The AGPLv3 is ideal for projects that are intended to stay open-source and be shared with the community. It’s particularly useful for software that is likely to be used in web-based or networked environments where you want to ensure that modifications to the software remain accessible to others, even if they are running it privately on their servers.
Some examples of when the AGPLv3 might be the right choice:
* Web apps and APIs that offer a service to users.
* Collaborative tools or platforms that benefit from community contributions.
* Any software that should remain open, even when deployed as part of a commercial service.
Conclusion
The GNU AGPLv3 is one of the most powerful tools in the open-source world for ensuring that software remains open and accessible, even as the landscape of software usage changes. By addressing the growing trend of cloud-based software and SaaS, the AGPL ensures that developers who benefit from open-source code are obligated to share their changes with the community. This means that the freedoms provided by the AGPL, like the freedom to use, modify, and share software, extend into the modern age of web services.
If you’re building software that’s going to be used over a network or want to ensure that your contributions to an open-source project remain accessible to everyone, the AGPLv3 could be the perfect choice for your project.