AGPL Overview

The GNU Affero General Public License or GNU AGPL is a free software license published by the Free Software Foundation. The GNU AGPL is similar to the GNU General Public License, except that it has an additional section to cover use over a computer network. It closes what is commonly known as the Application service provider loophole of the GNU General Public License. The additional section requires that the complete source code be made available to any network user of the AGPLed work, typically a web application. For the legally precise description see the external link at the end of the article.

The Free Software Foundation recommends this license for any software that will commonly be run over the network.

Note that GNU Affero General Public License is not the same legal document as the Affero General Public License, though they are quite similar in intent and effect.

Comments

Note about “protection”: the AGPL only requires a hosted application or system provider to provide access to their source if they have modified the software.

Note that the AGPL is less "combinable" than the GPLv3. Here's what GNU has to say about this:

“Please note that the GNU AGPL is not compatible with GPLv2. It is also technically not compatible with GPLv3 in a strict sense: you cannot take code released under the GNU AGPL and use it under the terms of GPLv3, or vice versa. However, you are allowed to combine separate modules or source files released under both of those licenses in a single project, which will provide many programmers with all the permission they need to make the programs they want. See section 13 of both licenses for details.”

The best chart I've seen on license compatibility with the GPL is found at http://en.wikipedia.org/wiki/List_of_FSF_approved_software_licenses

Based on GPLv3, but has an additional term to allow users who interact with the licensed software over a network to receive the source for that program

“…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…”

FAQ

Q: Does that mean you cannot link against code you cannot release due to other license constraints? A: No it means that you need to distribute a link to the AGPL code your using, the other linked code bases are separate and governed by their respective licenses.

Think of it this way, if you go and create a SaaS platform using Enomalism, you need to provide your users with the original AGPL source code, this would probably happen via a link to the download location of our AGPL source code.

Pros

  • Provides more “protection” to commercial open source software companies by applying the viral property to SaaS (hosted) use
  • OSI approved
  • Builds on the wide use and acceptance of the GPL (V2.0)
  • AGPL is suitable for International use (GPL V2.0 was U.S. specific)
  • Patents are explicitly addressed

Cons:

  • This is a very new license, not yet broadly understood or accepted
  • Software under this license may not be combined with software under several other OSI-approved licenses
  • Copyleft clauses may inhibit adoption by (Open Source) customers due to compliance risk
  • The SaaS vendors and Hosting Providers will tend to avoid software under this license, if they think they might ever need to modify it.

Incorporated Licenses

Based on information provided 3/12 by Derek Anderson 
OpenSSL.SSL	LGPL, V2.1 License
base64	Python License
time	Python License
turbogears	MIT License
sqlobject	LGPL, V2.1 License
simplejson	modified BSD license
cherrypy	modified BSD license
boto	MIT License
elementtree	ElementTree Software License
MochiKit	MIT License (not AFL v2.1) 
Kid	MIT License 
FormEncode and PasteScript	Python license