pyqt4 & qt license

CM cmpython at
Sun Mar 10 04:31:21 CET 2013

On Mar 9, 9:08 pm, pitsa... at wrote:
> hello,
> i want to develop a GUI application that will be sold.
> i want to use pyqt4.
> can i download and use the GPL version during the development and then buy the commercial verion beofore i distribute the application ?

Arguably, yes.  From pyqt4's website:

"Yes, you can re-license your application under a commercial license
so long as you have purchased appropriate commercial PyQt licenses
before you start to sell it."

and also:

"The availability of the LGPL version of Qt means that it is possible
to evaluate using that and the GPL version of PyQt while still being
able to re-license any code written during an evaluation in a future
closed source application."

> commercial version means LGPL? i think i am comfused so please someone clarify on versions and licences.

There is currently no version of PyQT licensed with LGPL.  They refer
to their commercial license as
their "commercial license".

> somewhere i also noticed that there is a qt license ? will i need this also ?

Yes.  PyQT is a wrapper for Python around QT, so you would need both.
QT has, according to the site,
both a GPL and LGPL version of their license.

You can read up on GPL and LGPL by Googling about it, but in a
nutshell, for commercial applications,
of the two, LGPL is what you want.

Do you know about PySide?  It's another wrapper for QT that is
licensed as LGPL and is free software.
I don't know it's current state of development, though.  Last Twitter
update was about a year ago.

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