Lars Knoll

New agreement with the KDE Free Qt Foundation and changes for the open source version

Published Wednesday January 13th, 2016
39 Comments on New agreement with the KDE Free Qt Foundation and changes for the open source version
Posted in Biz Circuit & Dev Loop, KDE, Qt

Open Source and the Free Software movement have always played a very important role in Qt’s history. From the very beginning, Qt has been available under both Open Source and commercial licensing terms.

This dual licensing approach has played a major role in turning Qt into the technology it is today. While the commercial business funds the majority of the development work, the open source version has helped us grow the ecosystem of users and provided us with invaluable feedback and contributions improving the product.

KDE Free Qt Foundation

To show our commitment to this dual licensing model, the KDE Free Qt Foundation was founded in 1998. It is a non-profit foundation ensuring that Qt will always be available under open source licensing terms. The agreement that governs this foundation has stayed mainly unchanged over the last 17 years. As a lot of things have changed during these years, we have been working with KDE over the last year to create a new and updated agreement that takes todays realities better into account.

Nowadays, we have many more operating systems that are relevant to end users than we had when the original agreement was signed. To account for this, the updated agreement does not only cover X11 as in the original contract (Android got added around 3 years ago), but all major desktop and mobile operating systems. This includes Mac OS X, Windows, X11, Android, iOS and Windows Phone.

We are also now taking into account the fact that Qt is being developed in the open, with many other people in addition to the ones working for The Qt Company contributing to it. To respect the work of these people, the new contract ensures that all contributions, even if they aren’t yet part of a released version of Qt, are covered by the agreement.

Finally, the new agreement contains updates to the license requirements The Qt Company has when releasing a new version of Qt. Let’s have a look at those.

New license requirements

The new contract changes the licensing requirements for the open source version of Qt. The purpose here has been to bring the licensing of Qt more in line with the philosophy of the Free Software movement.

Free Software is about the freedom of the user to change and modify the code and to redistribute and use these changed and modified versions of the code. LGPL version 2.1 (LGPLv2.1) that we have been using as our main license does not ensure this freedom in the most effective way. For that reason, the Free Software Foundation created version 3 of the GPL (GPLv3) and LGPL (LGPLv3) a couple of years back.

LGPL version 3 differs from version 2.1 in two fundamental aspects. It explicitly protects the right of the end user to not only compile their modifications, but also deploy and run them on the target device. This essentially prevents the creation of fully locked-down devices. Secondly, it explicitly includes a protection against patent claims from the entity distributing code licensed under LGPLv3. These two additions greatly help protect the end users’ freedom when using source code licensed under LGPLv3.

For this reason, we added LGPLv3 as a licensing option to Qt with Qt 5.4 back in 2014, and have published new Qt modules under this license.

In line with this, the new contract with KDE now removes LGPLv2.1 as a required license for the open source version. Instead, it now requires LGPLv3 (and GPLv2 to keep license compatibility with some GPLv2 open source projects) for all existing frameworks and GPLv3 for our tooling and new add-ons.

Changes to our product offering


Starting with Qt 5.7, we are planning to adjust Qt’s open source licensing to be in line with these ideas. At the same time, this allows us to open up the parts of Qt for application development that have previously only been available under commercial terms to the Free Software community, unifying the product.

So Qt 5.7 will not be available under LGPLv2.1 anymore. Instead, we will provide the different parts of Qt under the following licenses:

  • Qt Essentials: All Qt Essentials will from now on be licensed under LGPLv3, GPLv2 and commercial license terms.
  • Qt Add-ons: All Add-ons that are currently available in the open source version of Qt, will in the future be licensed under LGPLv3, GPLv2 and commercial license terms (Qt WebEngine in addition has a LGPLv2.1 requirement due to the 3rd party code from Chromium).Add-ons that were only available under commercial license terms in the past (e.g. Qt Charts and Qt Data Visualization) are now available under both GPLv3 and commercial license terms.
  • Qt Tools and Applications: All tools (Qt Creator, moc, etc.) will in the future be available under commercial license terms and GPLv3. The GPL license comes with two exceptions that ensure that there are no license restrictions on generated code, and that bridging to 3rd party code is still possible.

This means that all parts of Qt for Application Development can be used under the GPLv3. Most parts can additionally be used under the LGPLv3 and GPLv2. Compatibility with GPLv2 will be kept where it is currently in place. All LGPL-licensed libraries inside Qt stay available under LGPLv3.

We believe that this combination of licenses for Qt is the best possible option to grow the Qt ecosystem further in the future.

In the embedded space, LGPLv3 in essence prevents the creation of locked-down devices. So any Qt user will then either help the ecosystem by creating an open device that allows Qt developers to target a larger market, or help the ecosystem by funding further development of the product. For desktop and mobile applications, the changes compared to LGPLv2.1 are smaller, but there are important clarifications for example related to mandatory patent license in case of distributing under LGPLv3 or GPLv3.

Unified product offering

With the contribution of these previously commercial-only modules and tools, we are removing the feature delta between the open source and commercial versions of Qt for Application Development. Publishing these add-ons under GPLv3 makes these available to the Free Software ecosystem, while at the same time keeping the incentives for commercial users to buy a license and help us fund further development of Qt.

The modules newly available to open source users are:

Furthermore we will start work to integrate the Qt Quick Compiler functionality into the Qt QML module, targeting the Qt 5.8 release. At that point it will be available under LGPLv3/GPLv2/commercial license (the currently available Qt Quick Compiler will remain commercial-only for Qt version prior to Qt 5.8).

The source code for many of the modules has already been pushed to and we will push the remaining items in the coming days.

No changes to Qt 5.6 and Qt for Device Creation

Qt 5.6 and earlier versions will not be changed and continues to be available under the old licensing terms. Qt 5.6 is a long-term supported release, supported for three years after its release. We believe that this will give all users of the open source version enough time to adjust to the new licensing terms.

There are also no changes to Qt for Device Creation, which remains a commercial-only product.

Changes for commercial license holders?

It’s important to note that there are no changes to the commercially licensed version of Qt. But, we are convinced that these changes to the open source version will result in indirect benefits also for our commercial customers.

We believe these changes to lead to a better and more feature-rich Qt. This is due to the fact that the previously commercial only parts of Qt for Application Development will receive much broader testing and hopefully also contributions from the ecosystem. In addition, this change will help us extend the investments of The Qt Company into Qt and allow The Qt Company to focus more of its investments into the core part of the product.

Qt for Start-Ups

Over the last years, we have heard comments from many small companies and start-ups telling us that they would love to use the commercial version of Qt, but can’t afford the price of a full license. For these companies, we will in the coming months introduce a commercial start-up license for Qt for Application Development. This reduced-price offering will be limited to small companies and start-ups with annual revenue less than $100K.

Summing it all up

This change is the last step in a process we started about 1.5 years ago when we announced the one unified web site ( for Qt and that certain parts of Qt will only be available under LGPLv3 in the future. With this change, we can now fully unify our product offering. In the future, we will have one product called Qt for Application Development that comes with both commercial and open source licensing options.

The new licensing of the open source version of Qt is now much better aligned with our vision for Qt and the ecosystem around it. It is focused around the idea of a growing ecosystem where the open source version helps us extend the outreach and set of addressable devices for Qt application developers, and the commercial version generates the revenue to push the development of Qt as a product forward.

Feel free to also have a look at the corresponding announcement from KDE.

Also, for further information about the license change and Qt licensing in general, please see our updated licensing FAQ.

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Posted in Biz Circuit & Dev Loop, KDE, Qt


ekke ekke says:

Hopefully Qt for Startup commercial license will be available soon.

Would be great for Mobile APP Development where the full license doesn’t work for free or 0.99 apps or for custom apps developed by Independent Devs as I’m

Looking forward to order such a License 😉

JKSH says:

One word: Wow!

anon says:

was the kde qt agreement really with “no change in 17 years”? wasn’t it just “1 year”?

@anon: There has been many changes in the agreement throughout the years, but this time we did a major modernization and rewrite of the agreement to provide more clarity. Some of the history is described in the KDE Free Qt Foundation page at:

Frank says:

Will LGPL Qt apps be ok for distribution on iOS8+ since it supports signed dylib frameworks, like on OSX?

@Frank: iOS AppStore is problematic despite of possible dynamic linking, as Apple’s T&C are not well compatible with GPL or LGPL. Please check:

m][sko says:

Qt Quick Compiler functionality into the Qt QML module, targeting the Qt 5.8 release.

Best move ever!!!!! !!!!!!!
thx KDE and Qt professionals

Ariya says:

I think this is an example where a diagram or a table accompanying the explanation would be very useful and help clarifying the change!

Go Qt 🙂

Caleb says:

The patent statements in the LGPLv3 confuse me. In particular, the scope of the LGPLv3 patent license grant. Searching the Internet doesn’t help a whole lot, as I get mixed messages and statements such “Patent holders having claims reading on works they distribute have an obligation to refrain from enforcing those claims against parties to whom they distribute”.

Say I have a closed-source, propriety software application that uses the LGPLv3 version of Qt, and I meet all the LGPLv3 obligations (e.g. my application links dynamically to Qt). Can my software application (not Qt or a modification of it) have my patented software in it such that I can continue to enforce any infringements on the patent? Or does the LGPLv3 of Qt that my software dynamically links to require me to “refrain from enforcing those claims”?

FLHerne says:

The patent clause only applies to what you’re required to distribute under the LGPL – i.e. any modifications to Qt.

It doesn’t affect any non-(L)GPL code that you link to it.

James says:

According to Section 11(5), an unmodified distribution of GPLv3 software may lead to licence enforcement, specifically in cases where a third party grants a patent licence to the distributor (in this case you).
Again under Section 11(6), if a distributor (in this case you) grants a patent licence to a single customer, then the licence is automatically extended to all recipients of the software

Kevin says:

@James: I think it still only applies to the (L)GPL licensed code, in this case Qt.

I.e. if you grant a patent license for things implemented in Qt itself, then you grant to to everyone.

This does not affect any patent involved in the proprietary part of the application as far as I can tell

James says:

@Kevin: Section 11(5) talks about users of Qt conveying a “covered work”, which is a defined as either the unmodified Program or a work based on the Program. Thus the patent clause applies to the complete work and not limited to modifications in Qt.

Johannes Lochmann says:

Will Qt for Startup commercial also be available for single developers?

@Johannes: Yes, also individual developers will be able to purchase. It will be available online with credit card payment.

ekke ekke says:

please don’t wait too long to provide this new license type.
will order immediately

Johannes Lochmann says:

thank you very much!

Leandro Cerdan says:

Bravo Qt team! Thanks very much!

QMutex says:

The reduced-price commercial option sounds great! I’m in.

Jose says:

Awesome! Great move.

Paweł says:

Thanks Qt !

CSRedRat says:


David says:

Mixed feeling here.

Issue 1:

A good chunk of the “newly open” Qt add-ons should have probably been an open part of the main Qt project to begin with.

(e.g. Qt Quick 2D Renderer software fallback, Qt Charts, etc.)

When Digia purchased Qt, this balance really swung in the wrong direction. Hard.

And even now, making these “Open-but-not-LGPL” even is very worrisome. It fractures the license landscape even further.

Issue 2:

I don’t really see the point of moving to (L)GPLv3-“only” for Qt.

Let me explain.

Since Qt will always need to get a contributor agreement for any contributed code, the protections granted _to_ Qt from (L)GPLv3 are mostly a moot point.

In terms of Tivoization protections for a GUI tool kit like Qt, this is last decade’s battle.

Yes, there will be some near term commercial license wins for in-progress designs.

But, there are enough other options (AOSP, boot to HTML5) for “cheapskate” device designers to choose from going forward

Worse, on the desktop side, this is a challenging time for cross-platform GUI tool kits. (e.g. Windows 8/10, app store sandboxes, etc)

Qt does a lot right, and we need even wider usage amongst developers to help all of us figure this out.

Hampering Qt’s adoption with LGPLv3 and it’s maybe “too viral” patent grants is the last thing we need going forward.

The only upside I see:

A possible silver lining is the opportunity for Qt to better formally document the limits of LGPLv3 patent grants and re-linking issues.

Maybe even drive some formal license text updates from the FSF.

This would help wider LGPLv3 adoption in to other kinds of technology where the anti-Tivo clauses would really be helpful. (e.g. base compression libraries, etc.)

Anonymous says:

The only way this could be more beautiful would be if you used “Free Software” instead of “Open Source” there, since what’s in play is much more than just technical advantages, but also the digital well-being of people.

d3fault says:

Wow there’s a heck of a lot of change in this post. I’m for all of it, with the exception of:

>All tools (Qt Creator, moc, etc.) will in the future be available under commercial license terms and GPLv3.

Please reverse that decision. If you’re going to add exceptions for generated code, why not just use LGPLv3? GPL removes the ability to library-ize ™ portions of the applications. It’s important to me that my entire toolkit/framework is >= (free-er than or equal to) LGPL. It’s one of the reasons I chose to use Qt in the first place years ago.

David says:

Agreed. I like the way you phrased it.

It’s important to me too that my entire toolkit/framework is >= (free-er than or equal to) LGPL.

If some add-ons remain “commercial only”, that’s fine.

The current proposal blurs the lines in a bad way.

Please keep Qt fully LGPL.

Thank you

Paul Jurczak says:

Is non-commercial license version of Qt Data Visualization available now or I have to wait until 5.7 is released?

@Paul: Source code is available now: git clone
We are aiming to package it as part of Qt 5.7 open source release, in Qt 5.6 it will be only in commercial packages.

UserQt says:

Is non-commercial license version of Qt Charts available now or I have to wait until 5.7 is released?

UserQt says:

And even when an approximate release date?

@UserQt: Current plan is to release Qt 5.7 in May 2016.

@UserQt: Yes. Source is available at It works with existing Qt versions. Pre-built packages come with Qt 5.7 (planned for May 2016)

Amit Tomar says:

Great work Qt team for bringing in even more stuff under the Open Source version ! License for startups would be great!!!..

QtUser says:

When do you plan to release Add-In for VS2015?
And when it comes to support MSVC2015 in Qt Creator? instead MSVC13.

@QtUser: Qt Creator already supports VS2015 and with Qt 5.6 there will be pre-built binaries for it available. Visual Studio Add-In does not work any more with VS2015, it needs some re-work (not yet with Qt 5.6).

F.Haferkorn says:

Are there any measures planned to get Visual Studio 2015 running with Qt5.5.1 or later?
A plain console app will work,
but when trying to compile e.g. the audiooutput or spectrum Example does not work!

Robert Teminian says:

Thank you for your great footstep toward the open source community. Also the new pricing plan looks attractive. Go Qt!

Ouzel says:


is it possible to create closed-source plugins to the QtC and make own distributions/solutions based on them? Sources of the modified parts will be published.

James says:

As per my understanding, perhaps it could be possible with a commercial license.

Commenting closed.

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