<!--#include virtual="/server/header.html" -->
<!-- Parent-Version: 1.77 -->
<title>Why the GNU Affero GPL
- GNU Project - Free Software Foundation (FSF)</title> Foundation</title>
<!--#include virtual="/licenses/po/why-affero-gpl.translist" -->
<!--#include virtual="/server/banner.html" -->
<h2>Why the Affero GPL</h2>

<p>The GNU Affero General Public License is a modified version of the
ordinary GNU GPL version 3.  It has one added requirement: if you run
the program on a server and let other users communicate with it there,
your server must also allow them to download the source code
corresponding to the program that it's running.  If what's running
there is your modified version of the program, the server's users must
get the source code as you modified it.</p>

<p>The purpose of the GNU Affero GPL is to prevent a problem that
affects developers of free programs that are often used on
servers.</p>

<p>Suppose you develop and release a free program under the ordinary
GNU GPL.  If developer D modifies the program and releases it, the GPL
requires him to distribute his version under the GPL too.  Thus, if
you get a copy of his version, you are free to incorporate some or all
of his changes into your own version.</p>

<p>But suppose the program is mainly useful on servers.  When D
modifies the program, he might very likely run it on his own server
and never release copies.  Then you would never get a copy of the
source code of his version, so you would never have the chance to
include his changes in your version.  You may not like that
outcome.</p>

<p>Using the GNU Affero GPL avoids that outcome.  If D runs his
version on a server that everyone can use, you too can use it.
Assuming he has followed the license requirement to let the server's
users download the source code of his version, you can do so, and then
you can incorporate his changes into your version.  (If he hasn't
followed it, you have your lawyer complain to him.)</p>

<p>Both the ordinary GNU GPL, version 3, and the GNU Affero GPL have
text allowing you to link together modules under these two licenses in
one program.</p>

<!-- Added a link to rms' article here. If it can be improved, please do it! -->
<p>One problem which the

<p>The GNU Affero GPL does not address is the problem
of Software as a <a href="/philosophy/who-does-that-server-really-serve.html">
Service (SaaS).  It is impossible, as far as
we know, to address this problem with a software
license. <a href="/philosophy/who-does-that-server-really-serve.html">
[1] </a></p>

<p>SaaS Software Substitute (SaaSS)</a>.</p>

<p>SaaSS means the that users use of someone's network server, by others, someone else's web server to do
work which is their
own computing.  They have  This requires them to send their data to the server,
which does their computing for them, them and sends the results back to
them.  SaaS  SaaSS is a problem an injustice because the users cannot control the their
computing which the server does for them.</p> when it's done that way.</p>

<p>If some program on this server is released under the GNU Affero
GPL, it requires that the users have a way server is required to download offer the users the corresponding
source of that program.  That is good, but having this source code
does not give them control over the computing the server
does for them. done on that server.  It
also does not tell them what other software may be running on that
server, examining or changing their data in other ways.</p>

</div>

<p>We don't see any sensible way to address the SaaSS problem with
license conditions on particular programs.  Even to write a legal
condition to distinguish between SaaSS use and non-SaaSS use would be
a challenge, and if we had that, it is not clear what we would want to
require in the SaaSS case.  Thus, our solution to the problem of SaaSS
is simple: refuse to use it.</p>

<p>If a program is meant specifically and only for SaaSS, you
shouldn't write it.  But many programs are useful for a variety of
kinds of services, including some that are SaaSS and some that are
not.  It's useful to write and release these programs so people can
set up non-SaaSS services with them, and good to release them under
the AGPL.</p>

</div><!-- for id="content", starts in the include above -->
<!--#include virtual="/server/footer.html" -->
<div id="footer">

<p>
Please
<div class="unprintable">

<p>Please send general FSF & GNU inquiries to
<a href="mailto:gnu@gnu.org"><gnu@gnu.org></a>.
There are also <a href="/contact/">other ways to contact</a>
the FSF.
<br />
Please send broken  Broken links and other corrections or suggestions can be sent
to <a href="mailto:webmasters@gnu.org"><webmasters@gnu.org></a>.
</p>

<p> href="mailto:webmasters@gnu.org"><webmasters@gnu.org></a>.</p>

<p><!-- TRANSLATORS: Ignore the original text in this paragraph,
        replace it with the translation of these two:

        We work hard and do our best to provide accurate, good quality
        translations.  However, we are not exempt from imperfection.
        Please send your comments and general suggestions in this regard
        to <a href="mailto:web-translators@gnu.org">
        <web-translators@gnu.org></a>.</p>

        <p>For information on coordinating and submitting translations of
        our web pages, see <a
        href="/server/standards/README.translations.html">Translations
        README</a>. -->
Please see the <a
href="/server/standards/README.translations.html">Translations
README</a> for information on coordinating and submitting translations
of this article.</p>
</div>

<!-- Regarding copyright, in general, standalone pages (as opposed to
     files generated as part of manuals) on the GNU web server should
     be under CC BY-ND 3.0 US.  Please do NOT change or remove this
     without talking with the webmasters or licensing team first.
     Please make sure the copyright date is consistent with the
     document.  For web pages, it is ok to list just the latest year the
     document was modified, or published.
     
     If you wish to list earlier years, that is ok too.
     Either "2001, 2002, 2003" or "2001-2003" are ok for specifying
     years, as long as each year in the range is in fact a copyrightable
     year, i.e., a year in which the document was published (including
     being publicly visible on the web or in a revision control system).
     
     There is more detail about copyright years in the GNU Maintainers
     Information document, www.gnu.org/prep/maintain. -->

<p>Copyright © 2010 2010, 2013, 2014 Free Software Foundation, Inc.</p>

<p>
This

<p>This page is licensed under a <a rel="license"
href="http://creativecommons.org/licenses/by-nd/3.0/us/">Creative
Commons Attribution-NoDerivs 3.0 United States License</a>.
</p> License</a>.</p>

<!--#include virtual="/server/bottom-notes.html" -->

<p>Updated:

<p class="unprintable">Updated:
<!-- timestamp start -->
$Date: 2014/04/12 13:54:41 $
<!-- timestamp end -->
</p>
</div>
</div>
</body>
</html>