Qt pricing (most up to date)

Question

I am thinking about using QT for rich GUI commercial multiplatform programs. A would want to know how much the commercial license would cost.

I found just old prices (2008): https://stackoverflow.com/questions/352896/qt-commercial-licenses

1. I am interested for the actual price (even earlier to see how it rises) for: win+osx

2. The license is one time or I have to buy license yearly?

3. Is there anyone who uses the LGPL version commercially? (I know that it can be done but I might need to make changes to QT without releasing the code for it: https://stackoverflow.com/questions/2945612/qt-lgpl-licencing-for-a-free-application-with-closed-source)

4. Actually this price policy (We don't tell you the price! We will call you!) is really strange to me, should I rather stay away form QT? I just tried it (15-20 hours) so going with other technology (.Net and just for Windows by dropping multiplatform support) is still an option

Solution 1

I'm no lawyer, so I'm not an expert in this area. I just wanted to point out that you can still develop closed-source software using an LGPL license. The catch is that you can't edit the Qt libraries without releasing the changes under LGPL.

Related SO thread: https://stackoverflow.com/questions/94346/can-i-legally-incorporate-gpl-lgpl-open-sourced-software-in-a-proprietary-cl. Read the top answer to that question, there is a much better explanation there.

Unfortunately I can't help you with the pricing, but if you're not altering Qt itself then you may not need to pay for it at all.

Solution 2

I have used Qt LGPL in commercial closed source applications. Besides the minor inconvenience of dynamic linking, I see no reason not to.

Your concern in bullet 3:

I know that it can be done but I might need to make changes to QT without releasing the code for it

This is a very strange requirement. I don't know why you would want to hack on the Qt source, and then not release your changes to it. If you're comparing it to .Net, consider you wouldn't be able to make changes to that framework at all.

Comments

[Chris Parton]

Just for the record, the OP's question was edited after I made my answer, so most of what I said above has been addressed in the question. Either that or I did a horrible job of reading the question the first time around.

[David Havran]

Usually frameworks contains bugs so fixing them might be needed. Not releasing is good because it will mean extra cost (you can still get your changes to the original library by commiting them but it will take time till they will be released in the new version) Can you send a link for some commercial LGPL Qt program?

[karunski]

True frameworks contain bugs, but usually you just work around them, especially in terms of closed source frameworks. There's not much cost to posting a patch to changes you make to the library either; you only have to distribute it to your customers when they ask.

[karunski]

I don't know what terms closed source applications use to license Qt, other than the ones I have worked on. However it's not hard to find examples of closed source programs built with Qt.

[karunski]

One of the responses on this question is from a guy who published an app to the Mac App store using the LGPL Qt. stackoverflow.com/questions/4337855/…

[Stephen Chu]

Does submitting your changes to Qt as a merge request to Qt git repository qualify as publishing the changes?

[Martin Beckett]

@Stephen - not according to some strict interpretations of the LGPL. but personally I would find it easier to have diffs against a published build rather than have to merge your full version with everyone elses changes. If the patches are accepted and become part of the new tree then you cna just supply that

[Username Obfuscation]

The link to the related thread unfortunately now appears to be broken.

[Valentin H]

This is plain wrong! How often I have to consult screeming customers, who were mis-consulted by such experts. The problem is, they are not allowed to switch from Comunity to Professional license close before release. Qt requires that the entire development is done in Commercial from the beginning. You can't include a QString, without breaking LGPL requirement. Using LGPL Qt in closed-source code sould only work, if your Qt-based open source application loads at run-time not Qt-based code.