[PyQt] PyQt Licensing Issue

Adriano Gagliardi agagliardi at ara.co.uk
Wed Dec 9 15:49:49 GMT 2009

Sorry to butt in, but from your explanation then as long as you make no
changes to the Qt source code itself i.e. you use it as given, and you
purchase a PyQt licence you are then able to sell your PyQt-based software? 



Adriano Gagliardi MEng PhD
Project Scientist
Computational Aerodynamics
Aircraft Research Association Ltd.
Manton Lane

Tel: 01234 32 4644
E-mail: agagliardi at ara.co.uk
Url: www.ara.co.uk 
-----Original Message-----
From: pyqt-bounces at riverbankcomputing.com
[mailto:pyqt-bounces at riverbankcomputing.com] On Behalf Of Richard Esplin
Sent: 09 December 2009 15:32
To: pyqt at riverbankcomputing.com
Subject: Re: [PyQt] PyQt Licensing Issue

Your confusion is understandable, especially with the recent Qt licensing
changes made by Nokia.

However, the licensing changes make it much less expensive to use PyQt to
produce proprietary applications.

The key thing to understand is that you need a separate license for each
tool in your development stack. The Qt and PyQt licenses are different.

Qt is released under the LGPL. You therefore only need to release your
changes to the Qt source code itself. If you want to keep those changes
proprietary, you need a commercial license.

PyQt is released under the GPL. You therefore need to release all code you
build using PyQt unless you purchase a commercial license.

I previously had to avoid PyQt on client projects because of the costs of
the PyQt + Qt development stack. However, I think the cost of PyQt alone is
pretty reasonable.

I'm redirecting this email back to the list so that someone will hopefully
correct any errors I make in this explanation.

Good luck,


On Wed 9 December 2009 05:58:47 Prashant Saxena <animator333 at yahoo.com>
> Buying a commercial PyQt license is not a problem. But if in any case 
> I would be needing files(.dll or .lib) from Qt SDK then I am sure I have
to buy Qt's commercial license also and that would be too costly.
> Right now I haven't done any test but I'll compile some application 
> modules(.py) using (gcc+cython) for code protection as well as speed
gains. I don't if in this case PyQt's (.dll or .lib) files would do the job
or I would be needing Qt's files also.
> I do have a bit of confusion here.
> Prashant
> ----- Original Message ----
> From: Richard Esplin <richard-lists at esplins.org>
> To: pyqt at riverbankcomputing.com
> Sent: Wed, 9 December, 2009 12:55:01 PM
> Subject: Re: [PyQt] PyQt Licensing Issue
> If you don't want to give away your code, you should buy the commercial
> Richard
> On Wed 9 December 2009 00:12:45 james infield <bimbam09 at gmail.com> wrote:
> > Hello,
> > 
> > That might be slightly off topic what do you mean by "...I won't be 
> > including the source code..." ?
> > 
> > Is that your code or PyQt code ?
> > Is there a way to release without giving your code and/or PyQt code ?
> > 
> > bimbam
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