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Newby with Qt questions :)



  • Hi.

    I'm new to these forums (first post) and have not yet tried Qt. I am having trouble finding information on the website about pricing, licensing and more so I hope the Qt community can offer me some info.

    I am an individual developer and I want to create software to sell to the public.
    I want to be able to support as many platforms (desktop/mobile,etc.) as possible.
    I don't know what that specific Qt license is called but I'm wondering :

    Q1:
    How much is the Qt license which builds for all of the supported platforms : desktop, mobile, and are there any others?
    Can you also include what currency the Qt prices are in?
    I'm in the USD so I'm using USD and I may have to convert.

    Q2: If I purchase a Qt license am I able to use it 'unlimited' with no time expiration?
    I'm used to developing with another product that sells a license which does not expire or have any selling limitations.
    Meaning once I purchase the license I can still develop with it for many years without needing to pay for renewals. Of course I would not receive any new features or bug fixes from later versions without purchasing license renewals but the point I'm making is the product doesn't magically expire or disappear after any amount of time. For example, I still use my 2011 version of the product even though I own current 2014 licenses.

    I'm hoping Qt does not have a time limit on it's license use or a limited sales number that mandates a repurchase for continued development?

    Q3: Honestly, how is Qt quality/reliability?
    One of the main reasons I'm leaving the other product and am interested in Qt is because the other product has too many bugs and the company takes too long to fix them. That's why I'm still using a 2011 version of the product even though I own 2014 versions of it. The current versions are too unreliable.

    Q4: Are there any serious holes in Qt's ability?

    Q5: When a bug is encountered and a bug report filed, how long does it take the Qt company to fix the bugs and get that fix into the customer's hands?

    Q6: Does Qt have drag and drop user interface layout ability and if so does it work well?

    Other reasons I'm leaving the other product is they 'half-bake' their features.
    For example, they don't even support HTTP 1.1. The company's employee tells you to write it yourself !
    They don't correctly support SMTP sockets so it fails on some SMTP servers.
    Their Windows builds have flickering issues that the company doesn't want to fix because they say "It's not practical for them to fix."
    They also recently stopped supporting OS X 10.6 (over 10 million users) and didn't even have the decency to give customers advance notice of this huge blunder.

    They also do not respect their customer's privacy and try to force you to use your real name and a photo of yourself. If you don't you are labeled as something different 'is not verified' and that creates turmoil in their community.

    The company also allows specific customers they like (due to dishonest butt kissing of their product) to call other customers trolls when we list our concerns about the product's problems and faults. Even though it is a violation of their forum policy they never punish those certain butt kissing customers for insulting other customers.

    Completely unprofessional.

    I could go on listing many more improper business activity from this company but I'd rather not waste your time. I'm more interested in learning about Qt and finding out if it will fit my needs and budget?

    Thank you very much in advance for sharing your Qt developing experiences!

    Looking forward to your responses!



  • Why not use Qt under the GPL to try it out.

    If you like, it and you want to do commercial development, then you can buy the license to do so.


  • Moderators

    Hi and welcome. Hope you've found a new home now :D I won't comment on the other company you mention, as it's unrelated to this forum's purpose.

    Let's get rolling:

    That depends on what are your needs. If LGPL option is fine for you, then you do not need to pay anything. If you want full commercial license (which also includes additional modules like Qt Commercial Charts, Controls and a small but convenient expansion to Qt Creator), you need to pay. You need to contact Digia for exact prices, but in general expect something in 1500-2000$ range.

    Yes, you can use it as long as you wish to (AFAIK - again, check with Digia), but after a year you will stop receiving updates and will not be entitled to Digia's support anymore.

    Qt is an Open Source project, developed by several companies (with Digia holding the trademark) and volunteers. Code quality standards are very strict, the whole package full of unit tests, and the release team double-checks everything before a release. So in that respect, the quality is really high. On the other hand, we are still somewhat early in Qt 5 lifetime, some things are still not as smooth as they used to be in Qt 4. But the situation is really rapidly improving, Qt 5.2 is pretty solid.

    That question is really too broad. Qt consists of 1200+ classes, and has hundreds of add-ons (KDE Frameworks, chart and plot libraries, cryptographic libs, etc.). A lot of functionality is well covered, but obviously you will find gaps if your needs are exotic.

    That depends a lot. There are bugs that are open for years, while others are being fixed in mere minutes. In general, Qt is too big for the developers to fix everything in a timely manner, so recently people are complaining a bit. When you are a paying customer, the situation is a tad different, as Digia is likely to prioritize your request (AFAIK). Patch releases for Qt are released every 2-3 months or so. But the code is public, so you can always pull the patch before it's integrated into mainline.

    Yes and yes, but I'm not an expert in drag and drop, so I might be wrong :P

    Hope this helps.



  • Hi and thank you to you both for your help.

    I have been very busy so I have not yet downloaded Qt and begun to learn it. Hopefully this weekend I'll have time to download it and give it a try.

    Am I correct in understanding I can develop with Qt for free and then purchase a license when I'm ready to sell my application?

    If so that will be wonderful.

    This will be a slow learning process for me because I'm already overloaded with my work and personal life but I'm looking forward to it.

    Thanks again!

    -Tim



  • If I understand it correctly, under the LGPL, you are allowed to charge a distribution fee for your project. However, the source code must be freely available, including any libraries you may develop. You can also charge fees for support, but I think these are independent of the LGPL.


  • Moderators

    [quote author="MartinCook" date="1390655966"]If I understand it correctly, under the LGPL, you are allowed to charge a distribution fee for your project. However, the source code must be freely available, including any libraries you may develop. You can also charge fees for support, but I think these are independent of the LGPL.
    [/quote]

    Incorrect. When using Qt in "LGPL mode", your code can be distributed under any license, including proprietary ones. LGPL itself applies only to Qt libraries (so, if you modify - for example - QString class, you need to publish that code). Of course, you can choose to use LGPL for your project, too: then you are bound by it's requirements.

    Atlantis you can sell your software when using Qt in LGPL, you can even sell it if you choose GPL: neither of those licenses talks about money. They are about essential freedoms of the user and the code, not about pricing. But, naturally, every time you pay for Qt commercial license, the whole Qt Project gains, so I wholeheartedly advise doing so ;)



  • But can you sell a software product that is statically or dynamically linked to the Qt Libraries? Can you distribute the Qt libraries with your application and still charge money for your application?


  • Moderators

    [quote author="MartinCook" date="1390760567"]But can you sell a software product that is statically or dynamically linked to the Qt Libraries?[/quote]

    Yes, you can sell it. If you link statically and your own code is closed/ proprietary, you need to take a deep look (with a lawyer) at LGPL to make sure you are not violating it (usually it's better to link dynamically and then there is no problem here).

    When GNU was young, RMS was actually selling copies of his software, even though it's code was freely available to anybody. There is really no conflict here: GPL and LGPL are about the code, not the business.

    [quote] Can you distribute the Qt libraries with your application and still charge money for your application?[/quote]

    Yes. Definitely so for "standard" open source projects. Since Digia holds trademark to Qt, though, you might run into problems somewhere else. Better ask them directly if in doubt.



  • If somebody doesn't want to buy the license, but would just like to make a donation, can that be done?


  • Moderators

    I'd love to do that myself, but AFAIK it is not possible at the moment to donate to the Qt Project. I am thinking about proposing that on the dev mailing list, though.


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