Is this true, Qt lgpl license..

[tgreaves]

--- excert from a webpage

This makes it possible to build proprietary (Closed Source) Software for KDE - the *WORLD LARGEST* Desktop Manager for Linux - for FREE! Without paying license fees to Trolltech...

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How can you build closed source software with the lgpl license? Can this software be sold to the public without releasing the source?

[ComaWhite]

Yeah it does. Just don't expect alot of propertiary to be opened with open arms in the linux community except the flash, nvidia drivers, vmware etc

[wysota]

If your application is licenced under LGPL then you have to publish its sources. But if your application uses a component that is licenced under LGPL, only the sources of the LGPL component have to be accessible provided that all the conditions of using the software in the first place are met (i.e. you don't link the component statically).

[ComaWhite]

I thought that was GPL you was talking about. If you have to release your sources under LGPL then how are you able to develop closed source of it?

[fullmetalcoder]

@ComaWhite :

LGPL has been an available licensing options for apps based on Qt for a while (as a special exception to GPL, among others : BSD, MIT, Apache, and more licenses could also be used to develop Qt-based software but all these licenses follow the same "use pattern" as LGPL (see wysota's post above)). What has changed is that Qt itself is now licensed under LGPL so you can chose whatever license you want for your software provided you meet the conditions of LGPL (there is a very educationnal whitepaper on this topic on ICS website btw).

[wysota]

Maybe this will make things more clear. If you use a component that is GPL-licenced, your software has to be licenced under a GPL compatible licence as well. This is not the case with LGPL - if you use an LGPL component, your application can still be licenced under a completely different licence as long as you don't break any licencing terms related to the LGPL component you are using.