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Qt is a commercial and open source licensed product developed by The Qt Company, together with the Qt Project under the open source governance model.
In order to develop and distribute your product with Qt, you must adhere to obligations and definitions enforced by the licensing agreements.
Why is Qt licensed also under an open source license?
We believe in the Free Software movement where using software comes with certain rights, but also certain obligations. The license gives users four primary degrees of freedom when using Qt:
If you are not willing to respect these free software principles, we recommend you do not develop with Qt using the LGPL.
Can I use the Community open source version to develop my commercial product?
It depends on how you license and distribute your product. The free version of Qt is mainly distributed under the LGPL. Some parts under LGPLv2.1 and LGPLv3, other parts only under LGPLv3. You will need to fulfill the license obligations for these licenses when using Qt in your product.
What is the difference between LGPLv2.1 and LGPLv3?
LGPLv3 is the current version of the GNU Lesser General Public License. LGPLv2.1 is an older version and not recommended by the Free Software Foundation for new projects anymore. Both licenses have the same intention, namely to protect the freedom of users to use and modify the software licensed under LGPL.
LGPLv3 makes this intention very explicit. You have to provide means to the end user to install a modified version of the library licensed under LGPLv3 and run your software using that modified library. In practice, this for example refers to:
What are my obligations when using Qt under the LGPL?
If you are using Qt under the LGPL, there are a couple of obligations you will need to fulfill:
The above freedoms cannot in any way be restricted by other licensing terms. If an application is not fully following all the obligations as outlined above, it is not allowed to be distributed at all.
Which parts of Qt are licensed under LGPLv2.1?
Most of the libraries in the Community version (Qt Free Edition) are available under LGPLv2.1 and LGPLv3. Some of the libraries are only available under LGPLv3, these currently are Qt Location, Qt 3D, Qt Canvas 3D, Qt WebView, Qt Quick Controls and parts of Qt WebEngine.
Which parts of Qt are licensed under LGPLv3?
With very few exceptions, all libraries that are part of the Community open source version are available under LGPLv3. The exceptions are Qt WebKit, Qt Script and parts of Qt WebEngine which are licensed under LGPLv2.1.
Please note, that Qt WebEngine contains parts that are available exclusively under LGPLv3/Commercial and parts that are LGPLv2.1 only. So if you use the Community version (Qt Free Edition), you will need to honor the licensing terms of both licenses when using Qt WebEngine.
Do I need to worry about LGPL when using a commercially licensed version of Qt?
Usually, not. When using the commercially licensed version of Qt, we provide almost all of Qt under a commercial license terms.
A few modules in Qt, however, use code from the WebKit project licensed under LGPLv2.1. These modules are Qt Script, Qt WebKit and Qt WebEngine. So when using these modules, you will need to fulfill the license obligations of LGPLv2.1 (but not LGPLv3).
Please also note that you can avoid using Qt Script, as the Qt Qml module contains a fully functional JavaScript engine that can be used instead. This module is available under commercial licensing terms and doesn’t introduce a dependency to LGPL licensed code.
As a commercial license user, in practice, you only need to consider license obligations of LGPLv2.1, and only if you make use of Qt WebEngine or Qt WebKit.
How can I find out whether I can use the Community open source version of Qt?
It is always recommended to contact a lawyer familiar with open source licenses for a full review of your project to determine whether you can fulfill all of the obligations of LGPLv2.1 and/or LGPLv3. In case there is any doubt on whether the requirements of the LGPL can be met in full, the commercial licensing option of Qt is often the best choice to avoid legal setbacks.
Qt is a commercial and open source licensed product developed by The Qt Company, together with the Qt Project under the open source governance model.
In order to develop and distribute your product with Qt, you must adhere to obligations and definitions enforced by the licensing agreements.
Is there a difference between the commercial version bought online and the perpetually licensed version bought via a Sales manager?
The online version is offered as a term license subscription. The development license is valid only when there is an active subscription. The perpetual license is valid forever and can be renewed on an annual basis for support and updates (new releases).
Do you offer perpetual licenses?
Yes. We offer a perpetual license to Qt for Application Development and Qt for Device Creation.
What is a subscription license?
With a license subscription of Qt for Application Development you pay a monthly fee during the time you develop with Qt. You receive all updates, and can use support, as well as the online systems. After the subscription ends, you cannot develop with Qt any more, but the applications you created can be used.
Do I have to purchase a license for every developer in our team?
Yes. Each developer must have their own assigned Qt license. It’s not permitted to mix Qt commercial licenses with Qt LGPL licenses in one project.
Can I develop with commercial Qt and install Qt Creator to more than one of my computers?
Yes. You can install Qt and our development tools to as many computers as needed as long everyone using Qt has a valid commercial license. Our licenses are per individual, so all members of your project team using Qt need to have a license.
Can some developers in our team working on the same project use open-source version of Qt and some developers use commercial version of Qt?
No. Each developer must have their own assigned Qt license. Mixing Qt commercial licenses with Qt open-source licenses in one project/product is not permitted.
Is it possible for some developers in our team working on the same project to use the perpetual license and some developers to use the subscription / term license?
Yes. It is allowed to use both perpetual and term licensed Qt in the same team. Note that it is not permitted in the same project to have some developers using perpetual and/or term licenses together with the open-source version of Qt.
Can I continue to use my subscription / term license without keeping my subscription active?
No. It is not permitted to continue development if your subscription is not active. The rights to continue using the tools expire when the subscription is cancelled.
Can I continue to distribute my application after I have cancelled my subscription?
Yes. You are permitted to distribute, but without further development (for example it is not allowed to build a new version of your application without a valid subscription).
I have a perpetual Qt license, can I continue to use the product if I do not renew the license
Yes. You can continue to develop with the same version you purchased.
I have a perpetual license, can I continue to get new versions or updates and receive support if I do not renew the license?
No. You must have an active perpetual license in order to get new versions/updates and receive support from The Qt Company.
I have a perpetual license; can I renew it only for some members of my team?
No. The whole team has to have active development licenses in order to use support and to receive updates.
If I have started development of a project using the open source version (LGPL), can I later purchase a commercial version of Qt and move my code under that license?
This is not permitted without written consent from The Qt Company. If you have already started the development with an open-source version of Qt, please contact The Qt Company to resolve the issue. If you are unsure of which license or version to use when you start development, we recommend you contact The Qt Company to advise you on the best choice based on your development needs.
How long is the Start for Free / evaluation period?
The commercial evaluation term period is thirty (30) days. During that time, you can develop with Qt, but you are not allowed to distribute your applications before you purchase a paid license. After the free 30-day period, you need to either purchase a license or cease from using the free trial.
Do the Qt commercial licenses allow for easy publishing to the Apple App Store?
Yes. The Qt commercial licenses allow publishing to the Apple AppStore or other stores (including those that require static linking).
Which commercial Qt version grants rights to modify libraries?
All commercially licensed Qt versions allow modification of libraries for application development. If you need technical support related to source code builds of Qt, at the minimum, Silver support offered by The Qt Company is needed.
Do the commercial Qt license agreements grant the right to do static linking of Qt libraries with applications?
Yes.
Can I distribute Qt binaries in conjunction with my desktop / mobile application?
Yes. Distribution of Qt libraries in binary form in conjunction with the developed application is allowed under the Qt for Application Development license agreements. A separate agreement is not needed. The platforms for which you have the right to distribute are listed in your license certificate (in your Qt Account).
Do I need to have a distribution agreement to develop an embedded device with Qt?
Yes. A distribution agreement explaining the terms for distributing the Qt libraries is included in your Qt license agreement. When you create an embedded device you typically have ‘joint hardware and software distribution’, which is subject to a distribution fee, please contact us for more information.
What does a ‘joint hardware and software distribution’ mean in practice?
If you are making an embedded device with Qt, you most likely will have ‘joint hardware and software distribution’ as described in the Qt for Device Creation license agreement. This is subject to a distribution fee, please contact us for more information.
Does Qt commercial licensing allow for source code distribution of Qt libraries or tools?
No, it does not. Qt libraries may be distributed in binary form only with the application.
Is there a way to add a platform to the online installer without an agreement with The Qt Company?
No. You must contact us. We are happy to add more platforms to the online installer.
Under the Qt commercial licenses, can I add new functionality and distribute Qt Creator?
No. Distribution of Qt Creator is prohibited without a separate agreement with The Qt Company.
When will my credit card be charged?
Your credit card will be charged at purchase.
Is there a minimum subscription time?
We require an initial 3-month commitment and after that it is an automatic monthly renewal unless you cancel the subscription. Subscription fees are not refunded.
Can I cancel my subscription at any time?
You can cancel your subscription any time after the initial 3-month commitment period. However, note that when you cancel your subscription you will not be able to access Qt Creator and continue developing. Our tools are only available with an active subscription.
How do I cancel my subscription?
You can cancel your subscription from Qt Account portal payments page.
How do I change my billing details?
You can change your billing details, for example credit card number, from Qt Account portal payments page.
How do I change my subscription quantity or platforms?
You can modify your subscription from Qt Account portal payments page.
What credit cards are accepted?
We accept Visa, MasterCard and American Express.
Why can’t I make purchase even if I have an accepted card?
It may be that the card issuer does not allow recurring payments or that internet payments are disabled.
Please contact us if you have any problems with your payments.
Which currencies are supported?
USD.
How do you manage EU VAT (Value Added Tax)?
Companies in the EU will pay 0% if they provide a valid company VAT number that can be validated during the purchase process. In Finland ,companies pay 24% VAT, but they can claim the 24% tax fee via Finnish tax officials. Otherwise buyers must pay 24% VAT due to EU taxation. After purchasing, customers will receive a receipt to be presented to the tax authorities. Please note that the VAT number must be entered without spaces or punctuation and with country code.
Customers in non-EU countries don’t have to pay VAT.
Why does my VAT number not validate?
The EU-provided interface may be unreachable and therefore the VAT number cannot be validated.
The data in EU provided information may be incorrect and your number is not there or is incorrect.. In this case it might be a good idea to contact your local tax authority.
You can claim the 24% tax fee via your own tax officials.
How is my order delivered?
Once your purchase is complete, you will receive a welcome email with information about your Qt Account. You can begin your download via the Qt Account where you will also be able to get updates and log support cases.
Where can I see my current subscription status?
Please log in to your Qt Account.
Can I buy a commercial Qt license without Official Qt Support or Qt Cloud Services?
Yes, please see our offerings.
Please also see the Qt blog and press release regarding the upcoming Qt open source licensing change and product structure update.
Simply and briefly, what is happening?
The license agreement with KDE Free Qt Foundation has been rewritten. With the new agreement, Qt will be licensed under a commercial license, GPLv2, GPLv3 and LGPLv3, but no longer under LGPLv2.1. This affects all Qt development work, starting from now with Qt 5.7 development.
With the new agreement, The Qt Company will open source all the desktop and mobile relevant APIs and tools that were formerly available only under commercial license unifying these two versions of the Qt offering. The existing Qt Essential and Add-on modules will be licensed under commercial, GPLv2, GPLv3 and LGPLv3 licenses. The newly open sourced modules and Qt tooling will be available under commercial and GPLv3 licenses.
Qt for Application Development, our product for desktop and mobile platforms, will be available with identical content under both open source and commercial licenses, i.e. the open source users receive a lot of new functionality.
Qt for Device Creation, our product for embedded platforms continues to be available only under commercial terms. As the licensing of Qt is changing, those using open source Qt for embedded platforms need to check compatibility before migrating to Qt 5.7 or later version.
To make Qt commercial licensing also more obtainable by smaller companies, The Qt Company is introducing a start-up licensing offer for a full commercial license of Qt for Application Development during Q1 2016.
Why is Qt licensed also under an open source license?
We believe in the Free Software movement where using software comes with certain rights, but also certain obligations. Use of open source licensing gives users four primary degrees of freedom when using Qt applications or devices:
The Free Software community has thrived because of these rules, but there are also developers who never intend to observe these rules, and thus should get a commercial license. The Qt Company exists to support both sets with the dual offering.
I’ve never heard of KDE, why do you have an agreement with them about your licensing? What’s the history of Qt and KDE?
KDE is an international free software community, founded in 1996, producing an integrated set of cross-platform applications for desktop and mainly known for its Plasma Desktop environment, which is provided as the default work environment on many Linux distributions. KDE software is based on the Qt framework. In the early days of Qt, the KDE project and community was the biggest driving force in building the developer ecosystem around Qt.
In the very early days, Qt was already dual-licensed, but the source code was available under proprietary open source licenses. Compromises with KDE were sought to ensure that Qt would be available for their use under appropriate open source licensing even if Trolltech (the company that founded Qt) would be bought or go bankrupt. As a result, The KDE Free Qt Foundation was founded.
The KDE Free Qt Foundation is an organization with the purpose of securing the availability of the Qt toolkit for the development of Free Software and in particular for the development of KDE software. The Foundation was originally founded by Trolltech and the KDE e.V. (the legal non-profit organization behind KDE) in 1998 and it has a license agreement that ensures the availability of Qt under LGPL 2.1 and GPL 3 licenses for X11 and Android platforms. The license agreement has been updated couple of times over the years, mainly because of acquisitions around Qt.
Now the license agreement has been properly modernized with an update and rewrite, as well as extended to cover more mobile and desktop platforms.
In what way is the KDE Free Qt Foundation license agreement updated now?
The license agreement has mainly been updated in two parts:
Who actually owns and controls Qt?
Qt trademarks and most of the copyrights are fully owned and controlled by The Qt Company. The development work for Qt toolkit is done through the open source governed Qt Project by The Qt Company R&D and external Qt contributors. The Qt Project is an open ecosystem and infrastructure for developers and companies to contribute to Qt. All external contributions are licensed to The Qt Company allowing re-licensing under both open source and commercial terms.
The Qt Company has a binding agreement with KDE Free Qt Foundation to ensure the availability of Qt under certain open source licenses for desktop and mobile platforms. The open source community and availability of Qt is an extremely important part of the whole value proposition of Qt and something The Qt Company wants to commit to and drive forward.
Why are you changing from LGPLv2.1 to LGPLv3?
The main issue with LGPLv2.1 is that the written legal license agreement does not fully ensure the intention behind the license agreement. The Free Software Foundation that has created the license already updated the license to v3 in 2007.
Like the Free Software community, KDE Free Qt Foundation also wants to update the license into the modern (L)GPL version. The KDE Free Qt Foundation has now decided that GPLv3 and LGPLv3 are the best licenses in driving Qt forward as a unified toolkit both for the Open Source community and for the commercial Qt business. Existing Qt libraries will in addition continue to be available under GPLv2 to help keep compatibility with some parts of KDE that is licensed in a way that is only compatible with GPLv2.
With the new license options, The Qt Company now has the possibility to open source a lot of its formerly commercial-only libraries and tooling and to unify the developer offering for application development.
What is the difference between LGPLv2.1 and LGPLv3?
LGPLv3 is the current version of the GNU Lesser General Public License. LGPLv2.1 is an older version and not recommended by the Free Software Foundation for new projects anymore. Both licenses have the same intention, namely to protect the freedom of users to use and modify the software licensed under LGPL.
LGPLv3 makes this intention very explicit. You have to provide means to the end user to install a modified version of the library licensed under LGPLv3 and run your software using that modified library. In practice, this for example refers to:
Which Qt versions does the license change affect?
The change will be implemented with Qt 5.7. All the recent Qt versions already contain LGPLv3 as an option for all functionality. With Qt 5.7 the LGPLv2.1 license option is removed, thus the open source users should choose between GPLv2, GPLv3 or LGPLv3 for their applications. All the currently released Qt versions are unaffected, these remain licensed with the open source licenses as is. The Qt 5.6 release is also not affected by the license change, it remains available under LGPLv2.1.
Does this affect Qt Project? Is Qt Project going away?
No. Qt Project will continue as it is today, as an open source governed project for developing the Qt libraries and tools.
Through the new licensing options, The Qt Company will open source a lot of formerly commercial-only libraries and tooling to the Qt Project. In addition to being available, these libraries are also now open for contributions, further development and under wider quality assurance through the whole Qt contributor ecosystem.
Are you abandoning / alienating open source world with this change?
No, exactly the opposite. We want to unify the offering between the commercial and open source Qt versions, so that the developer experience is equal for the whole community and users can easily select the appropriate license for their need. In addition, we will make a lot more libraries and tools available for open source development under the Qt Project, allowing the whole Qt contributor ecosystem to work towards the same unified product.
We are a small company and we can’t afford the current commercial license, how I can continue developing with Qt?
We will be providing a commercial licensing solution for small businesses with annual revenue less than $100K, which will make commercial Qt application development on desktop and mobile platforms more feasible. This “start-up” license, for full use of Qt for Application Development, will be introduced during Q1 2016.
What modules are you going to open source with the change?
Immediately upon license change, The Qt Company will open source the following modules or tools under GPLv3
Also, in the future, all new modules created for Qt will be dual-licensed under commercial terms and either LGPLv3 or GPLv3.
Who cares about the LGPL version you are using?
You, unless you are using Qt under a commercial license. Your customers and end users care! LGPL is a copyleft license, which means that the license follows with your product to your end users and customers.
What is the consequence of not complying with the LGPL/GPL restrictions?
If software using these open source licensed libraries does not fully comply with the license obligations you will lose your license and related distribution rights.
I’m not sure if I’m in compliance with the licensing scheme. What should I do?
It is always recommended to contact a lawyer familiar with open source licenses for a full review of your project to determine whether you can fulfill all of the obligations of LGPLv3. In case there is any doubt on whether the requirements of the LGPL can be met in full, the commercial licensing option of Qt is often the best choice to avoid legal setbacks. We’re also happy to talk to you about your situation, but we aren’t in the position to provide any legal guidance.
How does commercial Qt licensing work? Do all my developers need to have a valid Qt license?
Qt is licensed per named developer, so all developers working with Qt libraries or tools should have a license of their own, which also gives them direct access to Qt Support.
If you are building and distributing applications for desktop or mobile platforms you should acquire a license for “Qt for Application Development”. This can be purchased directly from Qt Sales or through the online webshop via http://qt.io through a monthly subscription model.
If you are building and distributing devices you should acquire a license for “Qt for Device Creation”. This license can be purchased through Qt Sales. In this case, you will also need a separate distribution license for your devices.
Both of the commercially licensed products may be evaluated free for 30 days through http://www.qt.io under the commercial license, so that you can already start working with the proper commercial license.
Can I mix code written with Open Source Qt and commercially licensed Qt?
Your whole development team should be using the same license and they should be using it during the whole development lifecycle. Therefore, if you plan to use a commercial Qt license, you should have it in place at the beginning of your project work.
If you want to migrate from open source Qt to a commercial license, you should contact us directly to discuss about your options in practice.
Is it possible to distribute applications developed with open source version of Qt via public application stores?
Each application store has their own unique terms and conditions, which may or may not be compatible with distributing applications under LGPL or GPL licenses. Based on the current terms and conditions of some of the widely used application stores it should be feasible to fulfill LGPL and GPL requirements with Google Play store and Microsoft Windows store. Distribution via Apple AppStore is more challenging as the terms and conditions of the store are more restrictive regarding the freedoms provided by LGPL and GPL open source licenses. The commercial license of Qt is compatible with the terms and conditions of all the leading application stores and thus typically the best choice for distributing a closed source application in various application stores.
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