Conkeror is tri-licensed under Mozilla Public License Version 1.1, GNU General Public License Version 2, and GNU Lesser General Public License Version 2.1.
This choice of licensing was made in order to make Conkeror's terms of distribution compatible with those of Firefox and most other Mozilla-based software. This makes it easy for Conkeror to derive code from other tri-licensed programs, and to share back Conkeror's code with other Mozilla programs.
Any new code checked in to Conkeror must also be licensed with this same tri-license. This is to ensure that users of Conkeror can take and use all the code of conkeror under any or all of the three licenses.
Refer to the COPYING file in the Conkeror source tree for the full text of the licenses.