Note that some modules are not available under the LGPL. You don't get charts, data visualisation or any of the embedded tooling. LGPL does not require the pro

Note that some modules are not available under the LGPL. You don't get charts, data visualisation or any of the embedded tooling. LGPL does not require the project to be LGPL. It simply means that you must provide users means to link your program to a version of Qt that they've compiled, or you provide the source of the Qt distribution that you compiled to build your application. You can have a commercial, closed-source, application using LGPL Qt. "A program that contains no derivative of any portion of the Library, but is designed to work with the Library by being compiled or linked with it, is called a "work that uses the Library". Such a work, in isolation, is not a derivative work of the Library, and therefore falls outside the scope of this License." Contrary to popular belief you can even statically link an LGPL library and remain closed source, but you may need to distribute your object files so that someone can statically link a different library version with your code. I'm not sure what happens if you modify Qt in some way though, presumably you're still covered if you release the modifications you made. Full answer here: http://answers.google.com/answers/threadview/id/439136.html http://answers.google.com/answers/threadview/id/439136.html