\title Qt Open Source Edition
Open source software (also called "free software") is software that comes
with a license that gives users certain rights. In particular the right to
use the software, to modify it, to obtain its source, and to pass it on
(under the same terms).
Trolltech supports the open source software concept by providing the Qt Open Source
Edition. You can use this edition of Qt to create open source software, i.e.
software that is licensed under the GNU GPL or a similarly recognized
open source license. Trolltech's support of open source with the Qt Open Source
Edition has enabled large successful software projects like KDE, to
thrive, with thousands of developers around the world using the Qt Open Source
Edition at no cost to themselves. The Qt Open Source Edition is available for
Unix/X11, Macintosh, and embedded Linux.
The Open Source Edition can be downloaded from here:
It is also possible to develop commercial software using Qt, but to do
so you must buy a commercial license for the \link
commercialeditions.html Professional or Enterprise Edition\endlink. If
you buy a commercial edition of Qt you can sell your software for any
price and with any license you like. Thousands of commercial companies
use commercial editions of Qt to develop the products they sell.
If you use the Qt Open Source Edition, there are certain licensing
conditions that the GNU GPL imposes on you, to ensure that your users
enjoy the freedoms guaranteed by the GPL. Users are entitled to:
\i Run your software for any purpose.
\i Obtain and study your software's source code, and adapt it to their
\i Redistribute your software and its source code to others (under the
\i Improve or modify your software, and release these changes to the
These freedoms apply to all the source code for all the modules your
software is based on, regardless of whether they have been written by
you or by others. The freedoms also apply to any associated interface
definition files, and even include the scripts and control files used
to control compilation and installation of the executable; otherwise
users could not exercise their rights.
This means that you cannot use the Qt Open Source Edition if your software
must be built with any modules that impose conditions on you that
contradict the conditions of the GNU GPL, including, but not limited
to, software patents, commercial license agreements, copyrighted
interface definitions or any sort of non-disclosure agreement. In
these circumstances you must use a commercial edition of Qt.
See the \link faq.html FAQ \endlink for answers to frequently
asked questions on Qt Open Source Edition licensing and its implications.
More information on open source software is available online:
\i GNU GPL: \l http://www.gnu.org/
\i Open source licensing: \l http://www.opensource.org/
Information about Qt Commercial License Agreements is available at
\l http://www.trolltech.com/pricing.html. You can also email
If you are in doubt what edition of Qt is right for your project,