LGPL Questions

**mhoover** · 14th January 2009, 18:54

It sounds like the LGPL license is "less restrictive", but those who use the LGPL version of Qt have to comply in a way that 'companies may be uncomfortable with'.

Does anyone know if that includes providing your source code to the public? If not, what does it mean? It sounds like it has to do with the libraries or something ...

**ivan.cukic** · 14th January 2009, 19:02

LGPL essentially means that the library itself (Qt in this case) must remain Free/Libre/Open Source Software - so if you change something in Qt, you'd need to provide the sources alongside with the binary.

But, and this is a big /but/ that makes all the difference

, your program, if you only link it to the library, doesn't need to be FLOSS, and it can be proprietary. The same is with the GNU C and C++ standard libraries, GTK...

**wysota** · 14th January 2009, 20:48

What is important to add, if you want to statically link Qt with your application, you can't use LGPL licenced version (unless you provide everything required to recompile the application, sources included).

**maverick_pol** · 2nd February 2009, 04:02

Hi,

Please correct me if I am wrong:

If I have a VS 6.0 and need to port it to Qt 4.5 for win/lin/mac and basically I will port the GUI to Qt I can use the LGPL, am I right?
I am not going to modify Qt and am going to "use the LIbrary" rather then "base my work on the library".
If I can use the LGPL and "close" the code, still I have to provide the "object code" for the work? To whom?

Thanks

**wysota** · 2nd February 2009, 09:08

You should think about changing the compiler to something... more compliant :-)

As for your answers, you are correct. You have to provide sources of Qt to people who get the binary version from you.