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Qt 5.15 licensing update



  • Hello

    I'm a bit lost with the "new" licensing model.

    If I download qt via application & use prebuild qt official binaries. Do I need to purchase license if I want to sell my application? I'm linking agains dlls if I'm not wrong.

    Regards
    Dariusz


  • Qt Champions 2019

    @Dariusz said in Qt 5.15 licensing update:

    "new" licensing model

    What new licensing model do you mean?
    You still get LGPLv3 Qt and as long as you do not violate it you do not need to buy a license.




  • Qt Champions 2019

    @Dariusz Those are not license changes:

    • Installation of Qt binaries will require a Qt Account
    • Long-term-supported (LTS) releases and the offline installer will become available to commercial licensees only
    • New Qt offering for start-ups and small businesses for $499/year

    As I said there is still LGPLv3 version.



  • @jsulm said in Qt 5.15 licensing update:

    • Installation of Qt binaries will require a Qt Account
    • Long-term-supported (LTS) releases and the offline installer will become available to commercial licensees only

    The OP does not state which platform he is. I am Ubuntu. May I ask briefly here:

    • There will still be an apt-get release with my OS, won't there? So I will get binaries from whatever version happens to have been released with my Ubuntu, won't I?

    • And if that release happens to be one of the Qt LTS releases, I'll have a Qt LTS, right? Though I guess I won't get any patches (but then I don't think I get Qt patched versions once I have done my apt-get now, I just get left with whichever Qt release was frozen into the distro originally, don't I?)


  • Qt Champions 2019

    @JonB "There will still be an apt-get release with my OS" - of course. Those are build from sources by the distribution and do not come from Qt Company.
    I'm not sure about LTS as QtCompany seems to want to delay the branches for LTS for 12 months, but after 12 months you get it. And of course you still can build Qt by yourself from source even without Qt Account :-)



  • @jsulm said in Qt 5.15 licensing update:
    Thanks for answer.

    And of course you still can build Qt by yourself from source even without Qt Account :-)

    Never tried it, and hope I never have to. I just know it won't work for me, and anyway on my VM it sounds like I can expect to go away and leave it to compile for a couple of days (before it eventually freezes/runs out of memory)... :)


  • Qt Champions 2019

    @JonB Don't worry your Linux distribution will still do it for you :-)



  • I'm on windows.

    (I do realize I need a lawyer advice but for now perhaps you can enlighten me a bit more)

    From past as far as I understood, if I compile Qt myself I have to get a license for it, or make the version public + src for it ? If I want to use it in my commercial app.

    Or I can compile dlls and link against those dlls and I'm still within my "free license" rights?

    TIA



  • In almost all cases, as long as your end user can compile their own version of Qt and plug it into your commercial app then you are fine with LGPL



  • @VRonin Thank you! Glad to know I can still use it :- )



  • @Dariusz said in Qt 5.15 licensing update:

    From past as far as I understood, if I compile Qt myself I have to get a license for it, or make the version public + src for it ?

    The license requirements are the same if you are using Qt under the LGPL. It does not matter if you compile it yourself or not. In any case if you are distributing Qt with your software you need to either provide the source code by the same means as your own software (e.g. both as download on your website) or a written offer to provide the source code valid for at least 3 years. Furthermore, you need to provide the user of your software with a way for them to relink with different Qt libraries. If you are using DLLs this is already given. If you link statically you need to provide object files or libs of your software for the user to link the Qt libraries with.



  • @SimonSchroeder said in Qt 5.15 licensing update:

    In any case if you are distributing Qt with your software you need to either provide the source code by the same means as your own software (e.g. both as download on your website) or a written offer to provide the source code valid for at least 3 years.

    I think this is a requirement of GPL not of LGPL



  • @VRonin said in Qt 5.15 licensing update:

    I think this is a requirement of GPL not of LGPL

    It's what I thought for a long time as well. There was another discussion in this forum about this. Finally, we figured out that as of version 3 the LGPL starts by including the GPL and granting a few more rights. It does not rephrase the requirements for distributing the source code.

    Maybe I was a little bit unclear (if that is the confusion): You only need to provide the source code of Qt. In no case do you need to provide the source code of your own software when using Qt under the LGPL.


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