gobject-introspection has two licenses; one for the typelib library, and one for the tools. The scanner (giscanner/) and typelib libraries (girepository/) are licensed under the LGPLv2+. See the file COPYING.LGPL. The tools (tools/) are licensed under the GPLv2+. See the file COPYING.GPL. There is also some MIT code in giscanner/. In general where applicable files should have headers denoting their license status; if they do not, please file a bug at http://bugzilla.gnome.org.