Using qt for a commercial application on windows (LGPL)

SGaist

Yes, with the software. Also ~~QMainWindow~~ QApplication has an aboutQt method that shows this information.

Jo Jo

@SGaist
I can't find the QMainWindow::aboutQt method in the documentation. Can you provide a link? I found QApplication::aboutQt but it gives us general information about Qt licensing (not specific to LGPL)

One more question: can anyone provide me with a link to a commercial Windows application that uses Qt under the LGPL license? I need such a program as an example

SGaist

@Jo-Jo My bad it was QApplication::aboutQt

zvoopz

@Jo-Jo said in Using qt for a commercial application on windows (LGPL):

can anyone provide me with a link to a commercial Windows application that uses Qt under the LGPL license? I need such a program as an example

I dont know which type of license does Viber use. I cant find any information about licenses inside this application but I see a bunch of Qt`s dlls here
C:\Users\username\AppData\Local\Viber
No Qt mention as well

Jo Jo

@zvoopz said in Using qt for a commercial application on windows (LGPL):

No Qt mention as well

Probably they are using commercial license but I am interested in example of app which releases under LGPL (no payment for Qt license, but commercial app)

Pl45m4

@Jo-Jo said in Using qt for a commercial application on windows (LGPL):

I am interested in example of app which releases under LGPL (no payment for Qt license, but commercial app)

I think it might be hard to tell, because to know this, you have to get the source code, which commercial app developers would not publish.
And AFAIK commercial Qt users can link Qt statically while keeping the code hidden. So as "customer" you are not able to tell whether such app even uses Qt.
Meanwhile, commercial LGPL developed apps you also have to buy first to inspect the files that are shipped with it.
(I don't have any apps I paid for, that were developed using Qt)

You could check the Windows App Store. Maybe there you find apps tagged with "Qt" (if there is such feature).
Or look into the Showcase subforum here. Maybe you find links to commercial apps that were developed by open source users here in the forum.

Jo Jo

@Pl45m4 ok, thank you!

SimonSchroeder

BTW, any app needs to comply with the same rules when using Qt under the GPL or LGPL. It doesn't matter if it's commercial or not. As soon as you distribute a binary (even if it is open source) you need to follow these rules. So, open source apps using Qt will suffice as example. Just note that just because someone else isn't doing something (e.g. not providing a download link for the Qt sources) doesn't mean this is the correct way to do it.

jsulm

@SimonSchroeder said in Using qt for a commercial application on windows (LGPL):

It doesn't matter if it's commercial or not

I disagree with this statement. As far as I know as commercial user you do not have to follow GPL/LPLG as you get Qt under commercial license, not GPL/LGPL (dual licensing).

SGaist

@jsulm said in Using qt for a commercial application on windows (LGPL):

@SimonSchroeder said in Using qt for a commercial application on windows (LGPL):

It doesn't matter if it's commercial or not

I disagree with this statement. As far as I know as commercial user you do not have to follow GPL/LPLG as you get Qt under commercial license, not GPL/LGPL (dual licensing).

I think @SimonSchroeder meant that when using Qt under GPL/LGPL, the fact that the application is commercial or open source does not change anything with regard to respecting these licenses constraints.