Nokia has announced that as of March 2009 its planned Qt 4.5 will be available under the optional Lesser General Public License. At the same time Nokia will open the Qt source code repositories to enable as easy an access as possible for further community development. The Finnish mobile giant took this step in an agreement with the KDE Free Qt Foundation. The company issued an FAQ to describe the LGPL move to the community and commercial interests.

The announcement on the new Qt webpage declares that Nokia wants to remove all hurdles from use of its software through the licensing change. It seems that the previous cost-based licensing had dissuaded many firms from implementing the Qt widget sets. The change is also an advantage for the open source community in that Qt also remains under GPLv3 licensing, with LGPL as an additional option.

Positive reinforcement for the move comes from KDE e.V. board member Sebastian Kügler: "Qt being available under the terms of the LGPL streamlines the licensing of applications built using KDE components on top of Qt-based applications. This more permissive licensing will further lower the barrier for adoption of Qt and KDE technologies. The KDE team welcomes opening up the development process and is looking forward to further improved collaboration between KDE and Qt Software."

The KDE project first and foremost welcomes opening up its repositories. KDE developers are thus free to fix Qt bugs without relying solely on the goodwill of Nokia. The KDE libraries are already under LGPL, thereby enabling commercial KDE application development such as for Mac OS X and Windows.

Ubuntu's Mark Shuttleworth also sanctioned the move: "Qt is used extensively in Kubuntu and KDE applications, and Canonical is delighted to see this breakthrough in its licensing model. Qt's new licensing terms will help us deliver ever more 'lustful' applications to users. Nokia's continued investment in cross-platform Qt libraries, and the Linux platform, is a major driver of innovation in the free software desktop and mobile device stack."

The licensing change will occur as of Qt 4.5, planned for March 2009. Nokia acquired Qt from Trolltech in January 2008 and is currently working on a port for the Series60 (formerly Symbian) mobile OS. The company has clearly indicated its commitment to Open Source over the last year.