It is free for commercial use? (Question about licence)

[tom_far]

Hi,

We will develop with my friend a program with C++/Qt and we will sell it (commercial). The application will work cross platform. We have some questions:

1) Which company (nokia...) develops the Qt as free for commercial use? Are The supported platforms (operation systems) less than the others? I mean is there any difference of these Qt?

2) Which IDE (free for commercial with QT/C++ entegration plugins) do you suggest for Linux? If I will write a code on Linux, I will use different IDEs to compile the code for different operation systems? If yes which IDEs do you suggest for other operation systems just for compiling the code?

2) This is little bit stupid question but I will ask it to be sure. C++ (with it's standart libaries) lincence is free for commercial use?

Thanks in advance

[high_flyer]

1. http://qt.nokia.com/products/licensing/
2. Qt Creator would be a good choice.
3 (which you wrote as 2). You don't need to pay license to use C++.

[Destiser]

Hi,

as far as I understand the license, you can make commercial applications with the free version of Qt, even close-source. But, any changes made to the Qt library must be open-source and the Qt library parts must be dynamically linked. This because Qt is free and open-source and the user must get acces to the openess of it, thus if it wants to change or update any Qt libraries used in your application, the user must be able to do this.

So, as far as you don't need to make any changes to Qt itself, and you don't need a 1-file-program, you can use the free license.

But, as I said, this is my interpretation of the license, and I'm no lawyer or somekind :p

C++ itself with STL is indeed free, as mentioned by high_flyer.

You can use QtCreator on Linux, Windows and Mac, it's a great IDE, so I would use that one.

[yeye_olive]

Hi,

as far as I understand the license, you can make commercial applications with the free version of Qt, even close-source. But, any changes made to the Qt library must be open-source and the Qt library parts must be dynamically linked. This because Qt is free and open-source and the user must get acces to the openess of it, thus if it wants to change or update any Qt libraries used in your application, the user must be able to do this.

So, as far as you don't need to make any changes to Qt itself, and you don't need a 1-file-program, you can use the free license.

This is not exactly true. LGPL-licensed software must indeed remain free in non-free derivative works. For a library such as Qt the usual way to achieve that is to use dynamic linking, thus allowing the user to replace the library without touching the application. Another less common way is to use static linking and provide the object code of the application. That way the user can replace the library and re-run the linker. A one-file binary is therefore feasible using the LGPL edition of Qt.