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Any definitive answer: "Qt’s open source licenses are not compatible with distribution on most app stores."

  • I was reading this article from 2014: Cross Platform Apps – Qt vs. HTML5. It states: "Qt’s open source licenses are not compatible with distribution on most app stores."

    Is this true? Is this a lie? A distortion? A confusion?

    It would be really really (e.g. really, really) nice if the owners and maintainers of Qt published a definitive, non-marketing statement on this.

    For instance.... I went to the main Qt site today to try to find out what a commercial license costs. I spent 20 minutes digging around menus and never did find out what it costs. I got offered "30 day free sign up" and some very vague "$350. per month" but there was really nothing CLEAR, STRAIGHTFORWARD, HONEST about what the costs are.

    Why is there not just a straight, simple page with options and costs?

    Seriously. I like Qt and am enjoying learning the framework but please – what the fcuk does it cost?
    Or... who are the the GPL police and how does that work?

  • I'm with you!
    I love Qt but sometimes we need to be advocate to understand the license questions...
    Also, there are some module under LGPL 2, others under LGPL 3 ecc....

    I think having some "lite" license mechanism should be very usefull.

  • @luca

    Oh yeah. I wonder if anyone from Qt...the company reads these forums.

    Hiding the cost of a license on their web site? (Yes, I clicked around for 20 minutes and still couldn't get a clear answer).
    I saw on another web site that the rate is $350./mo.... $4200. per year? And I have to ask: why am I learning this framework?

    I like Qt but ... many parts of it are only half complete (yes, looking at you, Bluetooth support) and despite "apparent" support for many features, reading the very fine print (and/or wasting days trying to get something to work) one finds that many features are not supported on all platforms, Borderline deceptive advertising? (looking at you AudioProbe Class).

    OR maybe most developers don't care about GPL or licensing and it is all a sham – there are no GPL "police" and there is nothing to be concerned about. So it doesn't matter to them that things are pretty glitchy and the docs are not to be believed? Of course no one will come out and say: use it however you want and don't worry about it (even if that is what most experienced devs do).

    Me? I'd like to do the right thing but nothing from the owners of Qt is making it clear what that is or how to do it.

  • Yes, we do read these forums.

    Yes, all platforms do not support everything possible, but you do realise that every single platform is evolving all the time and trying to keep up with them on all the details is hard work. Hard work that the developers of Qt are doing pretty well.
    (I agree with Bluetooth being a pain, as I'm trying to write something with it myself. Luckily the platforms I want to run on have pretty good support.)

    Next the legal questions.
    You also need to understand that I have zero hours of law school or training, so getting a comment from me about licenses in third party app stores is like asking a random person on the street. Add to that the fact that some people will take anything as legal advice, and the result is that we do not really like to say anything out here.

    As a general guide; and do not mistake this for legal advice, this is a random dude on the internet rambling about licenses.
    I have not read what the Apple app store texts say currently, but the text used to be hostile toward open source licenses (again stress on the part where I have not read it recently, I hear they are softening the text).
    Google has been more simple in the past, where LGPL Qt has been quite ok, there is even ministro that can handle the libraries for you.
    So it's Apple that has been in the gray area where people without a legal degree can't say anything in any direction.

    Then again, if you comply with the GPL/LGPL in providing the source/object files when someone asks, you are ok. (except if the Apple agreement says something else)

    We do have a commercial option for small business coming out this spring still. The cost will be in line with what a small business / indie developer can afford. So nothing like the 350$/month you found (which is probably about correct for a pro app development license).

    So assuming you want to do commercial apps, you can do open source and be prepared to give object / source files depending on the license you go with, or you can get a commercial license. Again assuming you are a small business / indie developer I suggest you wait a bit for the small business license that we have coming out in roughly the Qt 5.6 release timeframe.

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