KDE develops Free, Open Source Software. Most of the KDE software uses the Qt library, which is available under compatible free licenses. The continued availability of Qt as Free Software is safeguarded by the KDE Free Qt Foundation, founded in 1998. Recently, the foundation was able to conclude an updated agreement with The Qt Company that extends the scope of the protection and allows a license update.
More platforms included
The old agreement already offered protection for X11 (i.e. Desktop Linux) and for Android. The new agreement now also extends to Microsoft Windows, Microsoft Windows Phone, Apple MacOS and Apple iOS. They must be covered by the Free Software release of Qt as long as they are supported at all by The Qt Company. The protection for Linux is even stronger: Support for X11 and Android cannot be dropped at all. The Foundation also has the right to update to supported successor platforms (e.g. from X11 to Wayland) without additional negotiations with The Qt Company.
More code to be available as Free Software
With the new agreement, The Qt Company honours the request of the KDE Free Qt Foundation to release the commercial features as Free Software. The Add-ons will be released under the GPL (version 3, and 2 in most cases). This means that developers of GPL applications will have have access to even more Qt modules than in the past.
Most parts of Qt are currently available under the LGPL license, which can be used both for Free Software and for proprietary software. The new agreement continues with this approach while making some changes in the details:
In summary: All parts of Qt are available under the GPL (version 3) or under a compatible license. Most parts are also available under the LGPL and under the version 2 of the GPL.
Compatibility with existing licenses
The terms of the license update have been carefully negotiated to allow full license compatibility with existing users of Qt:
The new licensing will be applied with Qt 5.7. The long term support release Qt 5.6 will stay with the old licensing.
Qt Open Governance
Since 2011, Qt is developed by an open community under a meritocratic governance model. KDE developers have become major contributors to Qt. The new agreement between the KDE Free Qt Foundation and The Qt Company takes this change into account. New clauses protect the free license of all publicly developed code – even when it has not yet been included in a Qt release.
Past and future
The KDE Free Qt Foundation already played an important role when Nokia bought Trolltech, the original company behind Qt, and later sold Qt to Digia, which then founded The Qt Company. The contracts are carefully worded to stay valid in cases of acquisitions, mergers or bankruptcy. The history of the past 17 years has shown how well the legal set-up protects the freedom of Qt – and will continue to protect it in the future.