@Joe-von-Habsburg There are, I assume, numerous online product activation services like LicenseSpring (no affiliation or recommendation).

You could roll-your-own with something like Partial Key/Serial Validation or something similar.

Hi,

You can add:

<author> SPDX-FileCopyrightText: Copyright (c) year name_of_copyright_holder email_of_copyright_holder SPDX-License-Identifier: GPL-3.0-or-later </author>

Note that this is not specific to GPL. Whatever license you use, you shall make it known. There are several possible ways to do it. I would recommend following the SPDX format. It's simple to manage and you can use the reuse tool to help you ensure you have all what is needed in your software sources.

You never have to publish (i.e. making it public to everyone) your code. At least that depends on the mode of distribution.

The GPL only places requirements on you when you give your software to someone else. Everyone who receives your software is also eligible to your source code (under GPL, not under LGPL). So, if you give your software to one or two people you also have to give them the source code. If they decide to further give the software to somebody else, they also have to provide the source code to those people. If you put up your software for everyone to download on the internet, then you need to actually publish your source code. This all only applies to GPL. LGPL only means that this applies to the library (Qt in this particular case) and not your own source code. Also, you can provide a written offer valid for at least three? months to provide the source code to everyone who receives your software instead of giving them the source code directly.

Everything that is private and stays private does not have any requirements on the source code.

Thanks for the reply , yeah I was thinking same to contact sales team.

@JonB said in Qt License Inquiries:

@Braynex said in Qt License Inquiries:

I haven't decided yet whether to use Qt (C++) or PySide (Python).

Just to remind you of one thing. If you choose Python you must adopt the PySide you mention, either PySide2 or the new PySide6. Don't be tempted to pick the better known/more-featured PyQt5 or PyQt6 you will see around the web, because that requires GPL rather than LGPL. No such issue if you go C++.

Hi JonB, noted, thank you for the tips.

Our first choice is PySide6 for this project because PyQt's GPL licensing is out of the picture due to the nature of this project.

Kind regards,
Braynex

@rktech
How you write it does not matter. You must observe the LGPL terms of (most of, assuming you stick to that) Qt. Which means that you don't have to publish your sources, and if you do not alter the Qt sources you don't need to publish them either.

I am not a lawyer. This is an opinion, not legal advice.

@AndrzejB said in Licensing and shared objects:

Is possible static linking Qt libraries?

Yes.

Proprietary programs using Qt must uses second licence?

Closed-source programs can choose between:

LGPL Qt Commercial License

If your program is paid but your clients will get the code, you can use "normal" GPL, too.

And is possible create non GPL open source application using Qt , for example on BSD license?

Yes, as long as you use LGPL for Qt.

@daljit97 said in LGPL distribution in the Microsoft Store:

@sierdzio I suppose that could be an option I could consider, although I worry about piracy concerns.

Well, either worry about that or about Qt license costs. If you break the LGPL then you become the pirate ;-)

In this setup, if somebody gets the exe from you, they have already paid you. It does not solve the piracy problem, but does limit it somewhat.

You can use this app template:
https://marketplace.qt.io/products/qt-lgpl-app-template
Offers you a relink mechanism, also for embedded devices:
you can release a redistributable project (your application inside a compiled static library, in a qt .pro project)
and you must release your SDK (sysroot and compiler).
If you use Static Qt, user can build his own Qt and rebuild your closed source application.

i have the same problem ...
if you have education license you can sign in to your qt account and download qt-license file and save it to home directory this worked for me.

Some time ago Qt published webinar concerning the topic, which helped me a lot.

I am adding a link for future readers: https://resources.qt.io/videos/complying-with-the-requirements-of-the-gpl-lgpl-v3-license-on-demand-webinar

@ekkescorner Hi,
Well, when we develop a mobile app with Qt for Android and iOS (we'll use Start-Up Plan), if we sell the app a customer, Can this customer publish the app on Google Play and AppStore?

@Zeblote Should be fine as your updater just starts the game - it does not extend its functionality (means: your game is not derived work).

@Eeli-K That would mean you can't use github at all then since it isn't under your control. If github is considered "under your control" you can just fork Qt to your github account though.

I mean along these lines though no web server you don't actually own is truly under your control. And even then you are at the mercy of your internet provider even if it is physically your system. My company has quite a few web servers, but since things like AWS came around I don't buy actual hardware any more. AWS is not technically under my control even though I have root access to all the systems that are "mine".

You're right though. I don't think it would really be an issue, but people have sued over smaller things. The safe way is definitely throw up a copy on your own web server. Knowing it will never be downloaded by anyone just seems to make it such a waste of resources though.

@VRonin you probably need a software copyright layer to answer that :)

My totally layman understanding (and now I take my work hat off, as this is code owned by my employer) is that in Finland (and probably most of the EU) you would be safe if the code you are copying is practically the only way to do it, and it is so simple that it is the only reasonable solution to your problem, and that the part you are copying is short enough that could simply re-write it anytime, and you aren't copy pasting anything else from the same work.

The problem is that everything I'm saying above is way too hand-wavy to be of any use. It's always a case-by-case situation.

Linking has nothing to do with it. It is a question of does the copy-pasted material automatically bring it's license with it to your code.

If you wanted to be utterly safe, you would ask your friend, who has not seen the Qt code to implement a paintEvent once, and then use that. He probably would come up with about the same seven to ten lines of code. (clean room is the only way to be totally sure)

@ZeBe

Does the open-source licensing allow packaging a dynamically linked application and the required Qt libraries inside a single-file container

Yes, as far as I understand it, but I'm no lawyer.

@VRonin Thanks for the answer.
Just to be sure, this is my output when I run otool -L on my .app
Does that look ok?

@executable_path/../Frameworks/libopencv_core.3.1.dylib (compatibility version 3.1.0, current version 3.1.0) @executable_path/../Frameworks/libopencv_imgcodecs.3.1.dylib (compatibility version 3.1.0, current version 3.1.0) @executable_path/../Frameworks/libopencv_highgui.3.1.dylib (compatibility version 3.1.0, current version 3.1.0) @executable_path/../Frameworks/libopencv_imgproc.3.1.dylib (compatibility version 3.1.0, current version 3.1.0) @executable_path/../Frameworks/libopencv_objdetect.3.1.dylib (compatibility version 3.1.0, current version 3.1.0) @rpath/QtWidgets.framework/Versions/5/QtWidgets (compatibility version 5.6.0, current version 5.6.0) @rpath/QtGui.framework/Versions/5/QtGui (compatibility version 5.6.0, current version 5.6.0) @rpath/QtCore.framework/Versions/5/QtCore (compatibility version 5.6.0, current version 5.6.0) /System/Library/Frameworks/OpenGL.framework/Versions/A/OpenGL (compatibility version 1.0.0, current version 1.0.0) /System/Library/Frameworks/AGL.framework/Versions/A/AGL (compatibility version 1.0.0, current version 1.0.0) /usr/lib/libc++.1.dylib (compatibility version 1.0.0, current version 120.1.0) /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1226.10.1)

No you don't, again, just check what the LGPL license requires and conform to it, then you'll be good.