affero

Affero General Public License, commonly referred to as the AGPL, is a free software license published by Affero, Inc. It is a copyleft license that extends the GNU General Public License (GPL) with a requirement aimed at software that is run over a network. The central idea is to ensure that users who interact with an AGPL-licensed program over a network can obtain the program’s source code, including any modifications, under the same license.

Key provisions of the AGPL require that if you distribute or deploy a modified version of AGPL-licensed software to users, you must make available the complete corresponding source code under AGPL. The network-use clause means that providing access over a network counts as distribution for the purposes of the license. The license is designed to close the “SaaS loophole” by obliging service providers to share improvements.

Versions of the AGPL include AGPLv3 as the most widely used edition, published in 2007, which is compatible with the GPLv3. An earlier AGPLv1 exists but is largely obsolete. The AGPL is OSI-approved and maintained within the GPL family; it is sometimes chosen by developers who want to ensure freedom for users of hosted software as well as for those who run it.

Adoption and impact of the AGPL reflect its focus on software-as-a-service environments. It is favored by projects that rely on cloud or hosted deployments, as it prevents cloud providers from offering a modified service without sharing source code. Critics argue that AGPL can deter proprietary cloud offerings. While not as broadly adopted as some other licenses, it remains an important option in the free software ecosystem.