Qt in brief
Qt is a cross-platform framework for building applications with graphical user interfaces that run on Linux, Windows, macOS, Android, iOS and embedded systems.
Timeline
| Year | Event |
|---|---|
| 1991 | Haavard Nord and Eirik Chambe-Eng start work on Qt. |
| 1995 | First public release, version 0.90, on 20 May. |
| 2008–2011 | Owned by Nokia after the Trolltech acquisition. |
| 2014–today | Developed by The Qt Company, after a period under Digia. |
| 2026 | Qt 6.11 released on 18 March. |
What makes Qt different
Qt adds signals and slots for communication between objects: an object emits a signal, and any connected slot runs. This is a practical form of the Observer pattern. The meta-object compiler (moc) generates the extra code that makes this and runtime introspection possible in C++.
Licensing
Qt is available under commercial licences and under the GPL 2.0, GPL 3.0 and LGPL 3.0, which lets it be used in both proprietary and open-source projects.
Who uses it
Users include Tesla, BMW, DreamWorks, Lucasfilm and the European Space Agency, as well as many open-source projects.