Can I use Agavi in a proprietary, commercial application?
Of course. The GNU LGPL license explicitly allows this. An application built with Agavi is, in terms of the license, not a derivative work, but a work that uses the library: 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. Should you modify any of Agavi’s source code, you need to share these modifications with the world. In reality, this is not an issue with Agavi, since any functionality or behavior can be overridden or extended by subclassing or replacing Agavi’s implementations, which is perfectly fine with the LGPL: The LGPL contains no special provisions for inheritance, because none are needed. Inheritance creates derivative works in the same way as traditional linking, and the LGPL permits this type of derivative work in
