In general, the Hamlib project wants to make its software available for the widest possible use while assuring that further developments (in the library itself) are returned to the community for the benefit of all.
Most of Hamlib's source files, particularly for the front end library and for the backend libraries, are distributed under the "Lesser GNU Public License (v2.1)" - the LGPL.
Certain files such as various utility programs and example code files carry the "GNU Public License (v2)" - the GPL.
AUTHORS file is the canonical list of developers who have contributed as the Hamlib Group.
Please consult the developer list - firstname.lastname@example.org - with any questions about program licensing and distribution.