About the price of commercial uses



  • Hellow, I just want to ask some questions regards to the price. I just finished using the one months trial and I still want to keep practice on Qt Creator, Can I still use the Qt creator without paying the money(monthly 350 USD)? Also, whats the range that I can use Qt for free? For example, if I use the Qt open source to make a program and try to sell it, do I still have to pay for the license?

    Thank you so much


  • Moderators

    Yes you can use Qt Creator with the Open Source license. I don't think there is any use case which would force you to use the commercial version.

    Of course, you need to install the FOSS version - there may be some additional modules/ plugins in commercial Qt Creator and you are not allowed to use them under FOSS license (I'm not sure if there are any such plugins - there used to be in the past, but now I think they are all open sourced).

    Also, whats the range that I can use Qt for free?

    That depends on which license you choose: GPL or LGPL. There are many resources online describing in detail what rights these licenses grant you and what are your obligations. Please also note that some Qt modules (like Qt Virtual Keyboard or QtCharts) are available only under GPL license.

    For example, if I use the Qt open source to make a program and try to sell it, do I still have to pay for the license?

    No. Both GPL and LGPL do not put any restrictions on selling the applications, you can sell your app, moreover you can sell Qt as well (and your customers can do it, too). However, you have to fulfill the license rules.

    So, in case of GPL:

    • you have to provide your application source code, under GPL, to all your clients who ask for it (for free)
    • you have to provide Qt source code, under GPL, to all your clients who ask for it (for free)
    • your application has to be licensed under GPL
    • you have to inform your users that GPL license is used + provide license text

    And under LGPL:

    • you have to provide source code of Qt, to all your clients who ask for it (for free)
    • you have to inform your users that you are using Qt under LGPL + provide license text
    • you have to make it possible for your users to swap Qt version (replace Qt libs with their own version). That usually means that you have to link dynamically to Qt (.so on unix, .dll on windows, etc.)
    • you can't distribute on some platforms: iOS, probably Android - that's because they do not allow you to link dynamically
    • you have to make available any modifications you do to Qt itself (for example, if you change the source code of QString class) to all your users, under LGPL

    I'm in a bit of a hurry now, I might have missed some of the requirements. Research online and you'll get the whole picture.

    monthly 350 USD

    There is also the startup license, which costs 70$ per month.

    Also, Qt Company has some official info about licensing, here: https://www.qt.io/licensing/



  • Big thanks for your reply!!

    I couldnt find any information about the price of getting the GPL and LGPL license, do you have any idea about it?

    Thank you


  • Moderators

    @lucian123456789 said in About the price of commercial uses:

    I couldnt find any information about the price of getting the GPL and LGPL license, do you have any idea about it?

    It's free.

    http://qt.io/download-open-source



  • THANK YOU!!


  • Lifetime Qt Champion

    Hi,

    @sierdzio Apple relaxed the static linking rule, you can build Qt dynamically for iOS since 5.9 IIRC however it's not yet provided because the tooling is not yet completed to create fully functional packages without the need of manual developer intervention.


  • Moderators

    Cool, thanks for the info, Sam! :-)


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