Qt Android App in PlayStore?

  • Hi everyone,
    This is my first post and i'm hoping, that it is right placed here.

    My Question is: Is it possible/legal to sell a Qt Android App in the PlayStore or elsewhere?

    I know, that it's legal to sell a Qt Desktop application, if it's dynamically linked (LGPL license), but i don't know how the Qt Librarys are linked in the apk, so i'm not sure.


    P.S. Sry for bad english ^^

  • Moderators


    AFAIK, yes.
    See "publishtogoogleplay":http://qt-project.org/doc/qt-5/publishtogoogleplay.html. There's a line "you can publish your application on Google Play and monetize from it" in second paragraph.

    But not sure about the other store.

  • Thank you very much! (Also for the fast answer :D)


    Could it be, that they are talking about the commercial license for monetizing?

    See paragraph 'Hassle-Free Development. Monetize Immediately. '
    There they say: 'Qt Mobile comes with a convenient commercial license'

  • Moderators

    with the Mobile Edition license you wont have any problems.
    With the open source license you need to follow the LGPL guidelines.
    Meaning the either way you publish the full source code of your app.
    Or in case of a closed source app the user needs to be able to substitute the LGPL part (Qt) of your app. On Android this shouldn't be a problem. On iOS it is, since the apps are built statically.

    Read "this thread":http://qt-project.org/forums/viewthread/36189/ for example.

    But there are also possibilities to do so on iOS. It should be enough to distribute the object files of your closed source part. So the user can relink the application with his own Qt libs. But there is a "funny article":http://multinc.com/2009/08/24/compatibility-between-the-iphone-app-store-and-the-lgpl/ on the web which states that this is only possible when the user jailbreaks his iOS device to install unsigned custom built apps...
    But to sum up. To get a definite answer you are advised to ask a lawyer.

  • Thanks again for the detailed answer!

    I'm not that familiar with Android and it's apk's, soo.... how would it be possible for an user to replace the bundled qt libs (LGPL part) of my packed apk?

    Is it just like an archive? So that the following would be possible:

    unpack apk
    replace qt libs
    re-pack apk


    EDIT: I don't want to deploy my app on IOS, so that isn't a problem, thanks anyway

  • Moderators

    an "apk":http://en.wikipedia.org/wiki/APK_(file_format) file is an archive, yes.

    [quote author="realloc" date="1388657452"]So that the following would be possible:

    unpack apk
    replace qt libs
    re-pack apk

    basically yes.

  • Sorry for digging this one up but I am still unsure about how to handle this for the android play store.

    Since I have to "give prominent notice with each copy of the work that the Library is used in it and that the Library and its use are covered by this License", would it be enough to put the licensing information in a separate file in the apk?
    Or a notice in the app description in the play store?
    Or a note in a view in the app like "This app uses the Qt libraries provided under the LGPL, version 2.1. You can find more information in the license.txt file within the installed package"?

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