When launching a new project using Qt, you have to decide whether to buy a commercial license or use the free, open source version. It’s an easy decision. Free is better, right?

Well, not always. Here's why.

In a typical year, ICS works on more than 75 new and unique embedded devices based on Qt. Everything from a flying autonomous taxi service to lifesaving medical devices to an industrial control system for a shrink-wrap pallet machine. But despite the differences in these devices, every ICS proposal for our software development services includes the statement: ICS recommends that all of our clients use Qt commercial.

Why do we make this recommendation?

Qt commercial supports the Qt community by funding much of the research and development that keeps the whole Qt ecosystem at the forefront of cross-platform development. Still, despite our recommendation to support The Qt Company some of our clients struggle with the business decision regarding whether to use Qt commercial or the open source version of Qt.

Let me show you why in the vast majority of cases, Qt commercial makes business sense.

About the Qt Framework

The Qt Framework has a long a history of being provided under both commercial and open source licenses. In fact, it is arguably the key success factor (aside from the fact that it’s simply great software) behind Qt’s adoption and continued development by the open source community.

This strategy first resulted in its adoption as the fundamental GUI toolkit for the KDE desktop and its de facto adoption by the Linux community as the standard for developing user interfaces on Linux. This in turn resulted in the embracing of Qt as the user interface toolkit on real-time operating systems, such as QNX, Green Hills, Mentor and Wind River.

The latest release of the Qt Framework is available under a commercial license, both GPLv3 and LGPLv3. To simplify the discussion, I’m focusing on commercial Qt and LGPLv3.

So, when beginning a new project, why should you consider purchasing a commercial license when there’s a free, open source version?

In no particular order, here are some of the key reasons ICS strongly recommends its clients go commercial:

Reduced obligations/greater flexibility of distribution

Additional features

Technical support

License negotiation

Reduced Obligation/Greater Flexibility of Distribution

You’ve likely used libraries licensed under an earlier Qt version such as LGPLv2.1 or LGPLv2.0. Indeed, it would be difficult to create an application on Linux without using at least one library that was provided under the LGPL license. So why not use Qt under a similar license?

That same license, LGPLv2.1, is no longer available for Qt. The most recent version of the Qt Framework and all future releases of this software will be released under the LGPLv3 license. This is vastly different than the v2.1 (or earlier) license(s) that you might be familiar with. Significantly, LGPLv3 is not a standalone license. It is a series of exceptions to the GPLv3 license.

Anything not specifically given to you in the LGPL license reverts to the rights and obligations granted under GPLv3. If you are developing software that your company intends to patent, processes any digital rights media or is not re-linkable by the client (for instance, Class 2 and Class 3 medical devices) this referral to GPLv3 could make your lawyer very nervous.

Life is much simpler with Qt commercial. You can statically link your code, process any media you’d like (with or without DRM) and go for patents to protect your investment. Since all of ICS’ clients are pushing innovation, in nearly all cases all three factors are involved. Clearly, Qt commercial is the right business choice.

Additional Commercial-Only Features

It is pretty clear that the roadmap for The Qt Company continues to include the development of features and subsystems that are only available with the Qt commercial license. The most notable today are the QML compiler and the Qt Charts module.

Furthermore, the availability of features only under Qt commerical opens the door for The Qt Company to provide additional libraries through industrial partnerships (e.g. Qt Automotive). ICS sees the availability of Qt commercial-only features accelerating over the next few releases. In fact, stay tuned for a Qt Framework add-on by ICS, derived from our Viewpoint Interactive Solutions business, that is only available under Qt commercial.

One more thing: The cost of a developer far exceeds the cost of a Qt commercial license, and buying a commercial license with all of the currently available and future commercial-only features helps you optimize the productivity of your developers. That makes good business sense.

Technical Support

When you purchase Qt commercial, you get access to The Qt Company’s technical support team. Why is this important? ICS has regularly been called in to rescue first-time Qt development projects launched by companies with no access to Qt technical support. Sure, they could post specific development questions to various lists and hope for a timely answer, but they’d be tipping their hand to every competitor.

What makes most sense is to take advantage of the support available with a commercial license. And if this is your first Qt project, augment that support with the more expansive and project-specific technical assistance provided by ICS.

License Negotiation

Negotiation is not available for software provided under an open source license. You either accept all the obligations and limitations or you don’t use the software. While negotiation may not be an option with Qt commercial either (obviously we cannot speak for The Qt Company on this point), when you acquire a Qt commercial license there is at least someone you can talk to. That means you may have someone to negotiate with if your company has certain legal requirements, risk mitigation or regulatory requirements.

Fee is Better Than Free

People have a tendency to view free as superior to fee and disregard all the real costs of free. In the case of the Qt Framework, fee is the way to go. That’s why ICS recommends all our clients purchase a Qt commercial license. Of course, you should speak with an attorney who is familiar with software licensing so you can consider all the implications of open source versus a Qt commercial license both from a cost and legal point of view.

Considering developing a device or app using Qt? We can help you get the most from Qt commercial. Get in touch today.

*This blog does not constitute legal advice.