The GNU Affero General Public License (GNU AGPL, or AGPL) is a free, copyleft software license based on the GNU General Public License. Its defining addition is a rule for certain modified programs that people use remotely over a network: those users must be prominently offered access to the program’s Corresponding Source at no charge. The Free Software Foundation identifies version 3 as the latest GNU AGPL version.
What is the GNU Affero General Public License?
The GNU AGPL is designed to support cooperation with a community around network software. Like other copyleft licenses, it sets conditions on sharing covered software and modifications. Its additional network provision addresses a situation in which people use a modified program remotely without receiving a copy of it: under specified conditions, they must still be offered its source.
As an Amazon Associate I earn from qualifying purchases.
The FSF describes the AGPL as based on the GNU GPL with an additional term for users who interact with licensed software over a network. The official overview identifies version 3 as the latest GNU AGPL version: GNU Project: Licenses.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Scan for outdated or missing drivers - takes under a minute3Clear out junk files and repair common Windows errorsWhat does AGPL mean for SaaS?
Using software as a service does not, by itself, answer whether the AGPL’s network clause applies. Section 13 of AGPLv3 concerns a modified program that supports remote interaction through a computer network. It requires that the modified version prominently offer all users interacting with it remotely an opportunity to receive its Corresponding Source, by providing access from a network server at no charge through a standard or customary way of copying software.
#1 Best Overall
The important question is the interaction with the program, not whether someone calls it a server, a client, or a SaaS product. The GNU FAQ frames the issue as whether people reasonably expect to interact with the program remotely over a network. It gives proxy software as an example: the offer might appear on the landing page users see when they begin using the proxy. That example illustrates the principle; it is not a universal placement rule for every system.
Section 13 is conditional, not a blanket rule that every company using AGPL software must publish all of its code. The relevant facts include the precise license grant, whether the covered program was modified, whether it supports remote interaction, and how the program relates to other components. Whether a particular deployment meets the license’s terms depends on its facts; the license text and FAQ do not decide an individual system’s legal status.
Do I have to publish my source code if I use AGPL software?
Not necessarily. AGPLv3 does not simply require every user or operator to post every source file publicly. Section 13 describes an offer of the modified program’s Corresponding Source to users interacting with that program remotely when its conditions apply. Separate provisions address what is required when covered object code or source code is conveyed to others.
Free tools Windows power users keep installed
One-click scans. No signup required.
For a binary, the offered Corresponding Source should match that binary—particularly its program version—and be comparably accessible. The GNU FAQ says users need not be forced to download source just because they download the binary, provided both are made available as required. The FAQ explains this in Frequently Asked Questions about the GNU Licenses.
Rank #3
What counts as Corresponding Source?
In AGPLv3, Corresponding Source means the source needed to generate, install, and, for an executable, run the object-code work, as well as to modify it. It includes scripts that control those activities. The definition also addresses items such as interface definition files and libraries or subprograms specifically required by the work.
The definition has exclusions, including System Libraries and certain unmodified general-purpose tools or generally available free programs that are not part of the work. So Corresponding Source is broader than one main source file, but it does not mean every unrelated tool or piece of infrastructure used by an operator.
How does AGPL differ from GPLv3?
Both licenses include conditions for conveying covered works in object-code form. AGPLv3 adds section 13’s source offer for qualifying modified versions that support remote network interaction. That is the key distinction for a reader assessing remote use: GPLv3 has no equivalent AGPL section 13 network-interaction rule.
| Question | GNU GPLv3 | GNU AGPLv3 |
|---|---|---|
| What happens when covered object code is conveyed? | Terms for conveying covered works in object-code form apply. | Terms for conveying covered works in object-code form apply. |
| Is there an added network-interaction rule for modified versions? | No AGPLv3 section 13 equivalent. | Section 13 requires a prominent, no-charge Corresponding Source offer to users interacting remotely, when its conditions apply. |
AGPLv3 also expressly permits linking or combining an AGPLv3-covered work with a GPLv3-covered work into one combined work. Its text says the AGPL applies to its covered part and GPLv3 to the GPL-covered part. Do not assume that this treatment applies to other licenses or every component arrangement; check the exact license texts and how the components are combined. The full AGPLv3 text is available from SPDX: GNU Affero General Public License v3.0.
Best Value
- Used Book in Good Condition
What should maintainers check?
Before deciding what a project’s AGPL obligations are, identify the actual license grant and the way the software is used. The copyright holder’s wording controls whether a project offers AGPL version 3 only or version 3 or later; SPDX distinguishes these as AGPL-3.0-only and AGPL-3.0-or-later.
- Find the license and version for the exact component you use.
- Determine whether you changed that covered program.
- Assess whether people interact remotely with the modified program, rather than relying on labels such as “server” or “client.”
- Check how components are combined and whether you convey binaries or other copies to recipients.
- For an applicable source offer, ensure it corresponds to the relevant version and is accessible as required.
For notice-writing practice, the GNU Project recommends identifying the license in source-file notices and inserting “Affero” before “General” in the relevant GNU AGPL notice wording. Follow the complete license and preserve existing copyright and license notices. See How to Use GNU Licenses for Your Own Software.
AGPLv3’s network clause is not the only compliance rule
Section 13 supplements rather than replaces the license’s conveyance provisions. AGPLv3 includes requirements for conveying source and object-code forms. Section 6 also addresses Installation Information for covered object code conveyed in or for a User Product in specified transactions. These distribution rules are distinct from the network-interaction source offer; which rules matter depends on what is conveyed and how.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
