The GNU Affero General Public License (GNU AGPL) is a free copyleft license published by the Free Software Foundation in November 2007, based on the GNU GPL version 3 and the Affero General Public License (non-GNU).

It is intended for software designed to be run over a network, adding a provision requiring that the corresponding source code of modified versions of the software be prominently offered to all users who interact with the software over a network.

The Open Source Initiative approved the GNU AGPLv3 as an open source license in March 2008 after the company Funambol submitted it for consideration through its CEO Fabrizio Capobianco.

In 2000, while developing an e-learning and e-service business model at Mandriva, Henry Poole met with Richard Stallman in Amsterdam and discussed the issue of the GPLv2 license not requiring Web application providers to share source code with the users interacting with their software over a network. Over the following months, Stallman and Poole discussed approaches to solve the problem. In 2001, Poole founded Affero Inc. (a web services business), and he needed a license that would require distribution by other organizations who used Affero code to create derivative web services. At that time, Poole contacted Bradley M. Kuhn and Eben Moglen of the Free Software Foundation to get advice on a new license that would resolve this matter in GPLv2.

Around late February 2002, Kuhn suggested, based on the idea of a quine (a program that prints its own source code), that GPLv2 be supplemented with a section 2(d) that would require derivative works to maintain a "download source" feature that would provide complete and corresponding source code. Kuhn argued that there was precedent for such a requirement in GPLv2 section 2(c), which required preserving certain features by downstream distributors and modifiers.

Moglen and Kuhn wrote the text of the proposed new section 2(d), and provided it to Poole, who then requested and received permission from the FSF to publish a derivative of GPLv2 for this purpose. In March 2002, Affero, Inc. published the original Affero General Public License (AGPLv1) for use with the Affero project and made the new license available for use by other software-as-a-service developers.

The FSF contemplated including the special provision of AGPLv1 into GPLv3 but ultimately decided to publish a separate license, nearly identical to GPLv3 but containing a provision similar in purpose and effect to section 2(d) of AGPLv1. The new license was named the GNU Affero General Public License. Retaining the Affero name indicated its close historic relationship with AGPLv1. The GNU AGPL was given version number 3 for parity with the GPL, and the current GNU Affero General Public License is often abbreviated AGPLv3.

The finalized version of GNU AGPLv3 was published by the FSF on November 19, 2007.