GNU Affero GPL license: (trying to) debunking myths

There are a lot of misconceptions about the GNU AGPL license. I’m writing this brief article to try debunking them and explain what this license really is.

Let’s start from the GNU GPL. It makes a licensed piece of code (the covered work) forever free. If you download/receive a copy of a GPL’d software, you can use it in any way, study the code, modify the code, redistribute the software as is or a modified version. There are some limitations: if you redistribute the software, you can’t do things which limit the freedom of your users. For example, you can’t distribute the software as closed source.

This is considered as a strong limitations by non-free software producers and even by some free software producers. I completely disagree. Whoever can produce non-free software; but why should free software developers help them in doing so? Do non-free software developers help us in any way? No, they don’t.

However, GPL has a deficiency. The hey is the concept of distribution. If Jenny gives to Butch an USB stick containing a software, she’s distributing it. The same applies if she sends the software via email. In these cases, the GPL grants the basic rights of the end user. When the GPL was written, this was enough.

Nowadays, a software is often used via a network. No distribution takes place: Butch connects to Jessie’s server, and uses her copy of a software. He doesn’t receive the software itself, so the GPL cannot grant him any right. But… he is the end user! Most software users today don’t even know if the software they use is running on their hardware or somewhere else. In many cases, you just download a client. And no one even tells you it is just a client.

The AGPL addresses this problem. It is basically a GPL license with an additional clause: the section 13. This section is brief and very easy to understand (like most parts of the license) and the key part is: if you modify the Program, your modified version must prominently offer all users interacting with it remotely through a computer network (…) an opportunity to receive the Corresponding Source of your version by providing access to the Corresponding Source from a network server at no charge. This includes non-system libraries used by the software.

So, the AGPL simply does what the GPL cannot do anymore because we don’t run programs on our computers.

Of course you can use it on non-network software. It is generally a good idea: someday it might become network software, or a piece of your code could be used in a network software.

I can’t imagine possible reasons why one can honestly think that GPL is ethically right and AGPL is not. Of course there may be commercial reasons to pretend you think it. It depends on your company’s business model. If your company modifies GNU GPL software on your server, and you don’t want users to know this, then yes, you probably must pretend that AGPL violates your basic human rights.

License compatibility

There is however a caveat. Many people think that all free licenses can be used together. False: mixing incompatible licenses is just as illegal as copying Microsoft Windows for a friend. GPL is a great license which comes with a price: not all free licenses are compatible with it. AGPL is an even more free license, which comes with a greater price: even GPLv2 is not compatible with it.

Enjoy!

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