Can I modify Qt and use the modified source code?
Yes, you can modify the source code of the Qt framework. You can also distribute products using the modified source code, as long it is in object form. You can also share the modified source code with the Qt Company for possible inclusion in upcoming releases.
Why is the power of source code modification so decisive for many Product Leaders?
To appreciate the value of source code modification, it helps to look at what other UI and application frameworks allow. Many frameworks, such as some game development platforms, permit users to “look” at the source code. Some of the mainstream game platforms will allow the modification of their source code for commercial purposes depending on the license package. Some allow source code modification for "private" use, but such rights are more academic than helpful in business.
I don't want to diminish the significant value of understanding what happens inside the black box when you develop plug-ins or use APIs. But as we all know, “looking at” and “touching” are two very different things. The freedom to modify the framework source code can enable enterprises to implement short-term tactical and long-term strategic moves.
The Ability to Improve the Source Code
Production schedules and volumes might force embedded device makers to implement bug fixes themselves as a tactical resolution to reduce their impact. While the cross-platform vendor's job is to fix bugs in due time, the software world is not perfect. The ability to fix things yourself (when you want to) can significantly affect your bottom line, public reputation, or even your developer team's job satisfaction. It doesn't mean that you should be prepared to fix things yourself. You are paying after all for quality software. But as always, being able to make exceptions ensures your ability to control your destiny.
Personally, with 20 years of experience in steering software development, I'm always cautious when considering modifying third-party source code temporarily. However, I like having the power to decide whether to accept the disadvantages of branching away from the third-party code for a good reason.
Aiming at Strategic Differentiation
Product differentiation is essential to contrast your product from competitors. Without going too much into the aspects of product strategy, there are times you might want to modify the UI and application framework to stand out from the market significantly. Sometimes expanding the framework is just not good enough. While such strategic modifications come with long-term implications, such as higher service and maintenance expenses for the modified software, the freedom to differentiate should not be limited to things you develop "on top" of the application framework. This, by the way, might be the reason why many top game studios choose to build and maintain their own game development platform. Modifying a particular part of an application framework can be the jump start to product differentiation.
Selecting an application framework that allows source code modifications enables enterprises to create their own story, either at the beginning or during the lifetime of their product.
PS: If you want to see the details of your rights with Qt, then do check out chapter 2.3 (Modified Software) on our Terms & Conditions page.
