A better Qt because of Open Source and KDE

KDE and Qt have a legal framework for protecting Open Source Qt, named KDE Free Qt Foundation. I am one of two KDE people on its board. To explain a bit what we are doing, I have written a document “How the KDE Free Qt Foundation strengthens Qt”.

Background is the wish of The Qt Company to change some of the contract provisions. It is still a bit unclear which ideas exactly they are pursuing, but we will need to have a public consultation on them in any case.

My document is aimed as a reference to the current status quo, and to the history of the foundation. It is quite lengthy, but I hope that some of you find the content interesting enough to read it nevertheless.


The development framework Qt is available both as Open Source and under paid license terms. Two decades ago, when Qt 2.0 was first released as Open Source, this was exceptional. Today, most popular developing frameworks are Free/Open Source Software1. Without the dual licensing approach, Qt would not exist today as a popular high-quality framework.

There is another aspect of Qt licensing which is still very exceptional today, and which is not as well-known as it ought to be. The Open Source availability of Qt is legally protected through the by-laws and contracts of a foundation.

The KDE Free Qt Foundation was created in 1998 and guarantees the continued availability of Qt as Free/Open Source Software2. When it was set up, Qt was developed by Trolltech, its original company. The foundation supported Qt through the transitions first to Nokia and then to Digia and to The Qt Company.

In case The Qt Company would ever attempt to close down Open Source Qt, the foundation is entitled to publish Qt under the BSD license. This notable legal guarantee strengthens Qt. It creates trust among developers, contributors and customers.

The KDE Free Qt Foundation is a cooperation between The Qt Company on the one hand and KDE on the other hand. KDE is one of the largest Free Software communities for general purpose end-user software, founded in 1996. In case of ties, KDE has an extra vote, ensuring that The Qt Company does not have a veto on decisions.

My in-depth presentation below provides an overview of the history of the Foundation and describes its importance for Qt today. It explains in detail why the existence of the Foundation has a positive influence on the long-term market success of Qt.

Update 1: This document was written by Olaf Schmidt-Wischhöfer and published in December 2019 after receiving comments from the other board members of the foundation. In early January 2020, the board members representing from The Qt Company informed me that the text does not fully represent their views. I received no specific suggestions for textual changes.

Update 2: This document has not been updated to respond to the announcement of The Qt Company from 27 January 2020. I have not yet decided on publishing an updated version or not.

1 I use the terms “Open Source” and “Free Software” interchangeably here. Both have a long history, and the exact differences between them do not matter for the purposes of this text.

2 From the statues of the KDE Free Qt Foundation:
“The purpose of the Foundation is to secure the availability and practicability of the Qt toolkit for developing free software.”