PySide is a Pythonbinding of the cross-platformGUI toolkit Qt. It is one of the alternatives for GUI programming in Python to Tkinter, which is bundled with Python. Like Qt, PySide is free software. The project started out using Boost.Python from the Boost C++ Libraries for the bindings and later switched to the binding generator Shiboken to reduce the size of the binaries and the memory footprint.
PySide was released under the LGPL in August 2009 by Nokia, the former owners of the Qt toolkit, after Nokia failed to reach an agreement with PyQt developers Riverbank Computing to change its licensing terms to include LGPL as an alternative license.