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Can I use QT in a Freeware (Not Open Source) ?

  • Hi All,

    I want to develop and release a software as a freeware using QT but does not want to make the source code available (open source).
    Please guide me on the licensing part.

    Kindly advise whether I am allowed to do this. Thanks.

  • Well this question is more for lawyers from your country. But generally LGPL should be ok for you.

  • thanks qxoz.

    If QT is LGPL then why should I really worry about legal issues ?

    By GPL i understand : if a project is open source e.g the Linux Kernel then
    if you modify the kernel source and you are using the modified kernel in your commercial system , you will have to have to make those modified sources available to the public.

    But in case of QT, am not modifying the QT source code using QT to create new codes which belongs to me.

    When i think LGPL i relate it to BSD license.

    Please advise. correct me where applicable.

  • Moderators

    coolgod you are correct, broadly speaking. There are additional requirements, however (LGPL):

    • you are obliged to inform your users that your project is using Qt
    • you need to provide LGPL license text
    • on request, you need to provide Qt source code (yes, you need to do it. If Qt Project website is down, you still need to provide the source to the customer) and means to link your application with self-compiled Qt
    • you may need to provide licensing info about other projects Qt is using (Qt uses stuff from Apple and other companies, with many different licenses)

    That is why people usually encourage a visit to a friendly lawyer. Not that many of them know anything about software licensing... but they know the legal stuff better than programmers do :P

  • thanks sierdzio for this explanation.

    what legal issues can I have if i dont contact a lawyer (assuming am already following your guidelines)

    I just dont understand why it becomes so scary when it comes to licensing :)

    Do i need to contact or the contributors to the QT project ?

  • Moderators

    [quote author="coolgod" date="1397060824"]what legal issues can I have if i dont contact a lawyer (assuming am already following your guidelines)[/quote]

    Usually: none. Nobody, including your customers, will care about licensing. Unless you become ultra successful and other companies want to go on a court battle with you.

  • Hmm..i see.that's the problem when someone becomes very successful..
    thanks sierdzio for answering my questions.

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