Can I write programs in Qt and sell them as "closed sourced"?

Question

In reference to this question and that Qt is Qt GNU LGPL v. 2.1 , would it be correct to say/simplify:

Yes you can, but if you "enhance" the the Qt API you must publish it also?

Answer 1

That would be my understanding, yes.

See http://www.qtsoftware.com/products/licensing

To get a real answer, consult a lawyer :(

Answer 2

If I understand LGPL correctly:

• you can close your software
• you must link to Qt dynamically and be able to link to any version that has same interface
• any changes you make to Qt libs you must publish them
• in 'about' info you must include information that you use Qt, which version and link to license text