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QT Open Source Licensing

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  • N Offline
    N Offline
    Netzschleicher
    wrote on last edited by
    #1

    Hello forum community,

    some years ago I did something with Qt, but then nothing for a long time.

    Now I am thinking about getting back into Qt. But I am not sure about the open source history of Qt.

    I program as a hobby but I have my own GitHub account where I would like to make the one or the other program publicly available and offer ready to use binaries for download.

    Am I allowed to do this with Qt, or are there any pitfalls? If I am allowed to do this, what do I have to pay attention to? So, e.g. License Infos in the
    header and source files. I would definitely include the About-Qt dialog that is prefabricated by Qt.

    Maybe someone can help me.

    Greetings
    Netzschleicher

    sierdzioS 1 Reply Last reply
    0
    • sierdzioS sierdzio

      @Netzschleicher said in QT Open Source Licensing:

      Good morning,

      thanks for the quick answer. I was / am a bit confused because I read in many places that Qt changes the license terms from time to time and thus makes the use for open source programs without commercial claim difficult or unusable.

      It is true that Qt Company is very strongly promoting its business, and makes somewhat hard to find open source installer on its website, for example.

      But Qt itself is still open source and there are no plans to change it. What's more, it cannot change because of a special agreement between Qt Company and KDE - if QtC ever decided to close Qt, code and copyright would automatically get transferred to KDE under BSD license.

      N Offline
      N Offline
      Netzschleicher
      wrote on last edited by
      #6

      Thank you very much,

      i think i try to reactivate my Qt programming experiences.

      Greetings
      Netzschleicher

      1 Reply Last reply
      0
      • N Netzschleicher

        Hello forum community,

        some years ago I did something with Qt, but then nothing for a long time.

        Now I am thinking about getting back into Qt. But I am not sure about the open source history of Qt.

        I program as a hobby but I have my own GitHub account where I would like to make the one or the other program publicly available and offer ready to use binaries for download.

        Am I allowed to do this with Qt, or are there any pitfalls? If I am allowed to do this, what do I have to pay attention to? So, e.g. License Infos in the
        header and source files. I would definitely include the About-Qt dialog that is prefabricated by Qt.

        Maybe someone can help me.

        Greetings
        Netzschleicher

        sierdzioS Offline
        sierdzioS Offline
        sierdzio
        Moderators
        wrote on last edited by
        #2

        Most Qt modules are available under LGPL, all under GPL. As long as you fulfil the requirements of these licenses, you absolutely can publish on GitHub.

        You can get a nice summary of both licenses here: https://www.tldrlegal.com/license/gnu-lesser-general-public-license-v3-lgpl-3 and https://www.tldrlegal.com/license/gnu-general-public-license-v3-gpl-3

        (Z(:^

        N D 2 Replies Last reply
        2
        • sierdzioS sierdzio

          Most Qt modules are available under LGPL, all under GPL. As long as you fulfil the requirements of these licenses, you absolutely can publish on GitHub.

          You can get a nice summary of both licenses here: https://www.tldrlegal.com/license/gnu-lesser-general-public-license-v3-lgpl-3 and https://www.tldrlegal.com/license/gnu-general-public-license-v3-gpl-3

          N Offline
          N Offline
          Netzschleicher
          wrote on last edited by
          #3

          Good morning,

          thanks for the quick answer. I was / am a bit confused because I read in many places that Qt changes the license terms from time to time and thus makes the use for open source programs without commercial claim difficult or unusable.

          JKSHJ sierdzioS 2 Replies Last reply
          0
          • N Netzschleicher

            Good morning,

            thanks for the quick answer. I was / am a bit confused because I read in many places that Qt changes the license terms from time to time and thus makes the use for open source programs without commercial claim difficult or unusable.

            JKSHJ Offline
            JKSHJ Offline
            JKSH
            Moderators
            wrote on last edited by
            #4

            Hi, and welcome!

            @Netzschleicher said in QT Open Source Licensing:

            I read in many places that Qt changes the license terms from time to time

            Where?

            All current modules have retained the same licenses for years and years and years... Different modules may be released under different licenses, but they don't change licenses "from time to time".

            Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

            1 Reply Last reply
            2
            • N Netzschleicher

              Good morning,

              thanks for the quick answer. I was / am a bit confused because I read in many places that Qt changes the license terms from time to time and thus makes the use for open source programs without commercial claim difficult or unusable.

              sierdzioS Offline
              sierdzioS Offline
              sierdzio
              Moderators
              wrote on last edited by
              #5

              @Netzschleicher said in QT Open Source Licensing:

              Good morning,

              thanks for the quick answer. I was / am a bit confused because I read in many places that Qt changes the license terms from time to time and thus makes the use for open source programs without commercial claim difficult or unusable.

              It is true that Qt Company is very strongly promoting its business, and makes somewhat hard to find open source installer on its website, for example.

              But Qt itself is still open source and there are no plans to change it. What's more, it cannot change because of a special agreement between Qt Company and KDE - if QtC ever decided to close Qt, code and copyright would automatically get transferred to KDE under BSD license.

              (Z(:^

              N 1 Reply Last reply
              2
              • sierdzioS sierdzio

                @Netzschleicher said in QT Open Source Licensing:

                Good morning,

                thanks for the quick answer. I was / am a bit confused because I read in many places that Qt changes the license terms from time to time and thus makes the use for open source programs without commercial claim difficult or unusable.

                It is true that Qt Company is very strongly promoting its business, and makes somewhat hard to find open source installer on its website, for example.

                But Qt itself is still open source and there are no plans to change it. What's more, it cannot change because of a special agreement between Qt Company and KDE - if QtC ever decided to close Qt, code and copyright would automatically get transferred to KDE under BSD license.

                N Offline
                N Offline
                Netzschleicher
                wrote on last edited by
                #6

                Thank you very much,

                i think i try to reactivate my Qt programming experiences.

                Greetings
                Netzschleicher

                1 Reply Last reply
                0
                • N Netzschleicher has marked this topic as solved on
                • sierdzioS sierdzio

                  Most Qt modules are available under LGPL, all under GPL. As long as you fulfil the requirements of these licenses, you absolutely can publish on GitHub.

                  You can get a nice summary of both licenses here: https://www.tldrlegal.com/license/gnu-lesser-general-public-license-v3-lgpl-3 and https://www.tldrlegal.com/license/gnu-general-public-license-v3-gpl-3

                  D Offline
                  D Offline
                  dreiGeforce
                  wrote on last edited by
                  #7

                  @sierdzio

                  Thanks for these links. I must say that in short it's hard to tell the difference between the two.

                  Can you please clarify about whether which of the two is preferred to stick to when it comes to self-use or internal use (in a company)?

                  Thanks

                  SGaistS sierdzioS 2 Replies Last reply
                  0
                  • D dreiGeforce

                    @sierdzio

                    Thanks for these links. I must say that in short it's hard to tell the difference between the two.

                    Can you please clarify about whether which of the two is preferred to stick to when it comes to self-use or internal use (in a company)?

                    Thanks

                    SGaistS Offline
                    SGaistS Offline
                    SGaist
                    Lifetime Qt Champion
                    wrote on last edited by
                    #8

                    @dreiGeforce LGPL is fine. GPL is really nice if you want to ensure that everybody can do whatever they want with the original code.

                    That said, for enterprise uses, it would be nice to have a license to help fund the maintenance cost of Qt. Emphasis on: it would be nice. There are also circonstances where a commercial license would be better beside the access to support.

                    Note that if some internal tool you wrote would become a product, their will be some paperwork to do as you cannot just transition from the GPL/LGPL to Commercial like that.

                    Interested in AI ? www.idiap.ch
                    Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                    1 Reply Last reply
                    0
                    • D dreiGeforce

                      @sierdzio

                      Thanks for these links. I must say that in short it's hard to tell the difference between the two.

                      Can you please clarify about whether which of the two is preferred to stick to when it comes to self-use or internal use (in a company)?

                      Thanks

                      sierdzioS Offline
                      sierdzioS Offline
                      sierdzio
                      Moderators
                      wrote on last edited by
                      #9

                      @dreiGeforce said in QT Open Source Licensing:

                      @sierdzio

                      Thanks for these links. I must say that in short it's hard to tell the difference between the two.

                      Can you please clarify about whether which of the two is preferred to stick to when it comes to self-use or internal use (in a company)?

                      The core difference is: if you use GPL Qt, then your code also has to be GPL.

                      With LGPL Qt, your code can use any license you want, you just need to make sure you follow LGPL rules (inform users that Qt is used, allow users to swap Qt version with their own, etc.).

                      Companies typically prefer LGPL, but it is really not up to me to decide :-) Both GPL and LGPL can be used in commercial setting, with both licenses software can be sold. With GPL it is not possible to stop users from copying/ forking/ selling your code, though.

                      (Z(:^

                      1 Reply Last reply
                      1
                      • JKSHJ Offline
                        JKSHJ Offline
                        JKSH
                        Moderators
                        wrote on last edited by
                        #10

                        Note: The GPL and LGPL licenses are focussed on providing freedom for the software's users (as opposed to focussing on the software's developers).

                        The GPL guarantees more user freedom than the LGPL.

                        Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

                        1 Reply Last reply
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