I have recently started my own small development company and was looking at developing a framework to sell to clients. I discovered that there were many open source solutions already developed, licensed under the GNU Affero General Public License (AGPL).

I would like to know if I could use one of these and customize it to my own liking and market it as my own product. What would the ramifications of that be? Would I have to tell clients that the system consists mostly of free components?

The idea is to not sell the product itself but instead charge people for the use thereof on a monthly basis. This product will be web-based.

I have tried reading the licensing information but can't quite understand it. I would like to make 100% sure of what I can do before I run into any trouble.

The project in question is http://www.projectpier.org/

  • 2
    If you want to be 100% sure, shouldn't you consult a lawyer? Mar 15, 2016 at 12:53
  • I would, but I am sure there are some programmers out there who can provide me with advise before I need to pay to get told something that I could have been told for free
    – Dave
    Mar 15, 2016 at 12:55
  • 1
    Can you cite the specific portions of the license that you are confused about? They do have a FAQ that gives a pretty explicit answer to commercial use.
    – Jay Elston
    Mar 16, 2016 at 0:38
  • @JayElston thanks for the link, that pretty much answers my question!
    – Dave
    Mar 16, 2016 at 10:07

1 Answer 1


The GNU Affero General Public License (AGPL) is not that different from the GNU General Public License, but with considerations for software-as-a-service. Under the GNU GPL, you would not need to distribute your source code if you made modifications to a project released under the GPL, but provided it as a service. Under the AGPL, you must release your modifications.

This means that, yes, you will be required to make your source code available (per the terms of the AGPL) to your users. Since they will be given a copy of the license, they will know their rights to view, modify, and even redistribute the source or object code on their own.

The AGPL, like the GPL, doesn't preclude commercial sales of a product. However, you must provide your users with a copy of the license. Upon their request, you must also provide them with the source code. The AGPL does allow for an author to place additional terms on their product, such as requiring specific attribution in derivative works, prohibiting the use of the original product or product's authors in marketing material, or requiring that redistributed versions are rebranded.

This page from the FSF provides a pretty good overview of the AGPL.

  • So in short I could charge a fee for the use of the modified system but would have to provide the source code upon request?
    – Dave
    Mar 15, 2016 at 13:03
  • 1
    @Dave Yes. From the AGPL: It requires the operator of a network server to provide the source code of the modified version running there to the users of that server. Therefore, public use of a modified version, on a publicly accessible server, gives the public access to the source code of the modified version. Anyone who has access to the software also has access to the source code.
    – Thomas Owens
    Mar 15, 2016 at 13:05

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