The plugins will be linked to epiphany at run-time. Epiphany's license terms include the notice below. In order to be able to legally link to epiphany, the plugins' copyright terms include this notice as well: The present copyright holders of this program have given permission, as a special exception, to link this program with the Mozilla XPCOM library, libxpcom and to include header files for xpcom components when those header files are covered by the MPL or NPL licenses, as long as the GNU GPL is followed for this program in all other ways. If at a future time xpcom and/or used header files are dual-licensed, where one of the licenses is the GNU GPL, this exception clause ceases to apply for the dual-licensed code, and such code must be used under the GNU GPL.