This article analyses hard-coded domain blocking in open source software, using the GPL3-licensed Mastodon client Tusky as a case example. First, the
question of whether such action is censorship is analysed. Second, the licensing
compliance of such action is examined using the applicable open-source software
and distribution licenses. Domain blocking is found to be censorship in the literal
definition of the word, as well as possibly against some the used Google distribution licenses — though some ambiguity remains, which calls for clarifications in the
agreement terms. GPL allows for functionalities that limit the use of the software,
as long as end-users are free to edit the source code and use a version of the application without such limitations. Such software is still open source, but no longer
free (as in freedom). A multi-disciplinary ethical examination of domain blocking
will be needed to ascertain whether such censorship is ethical, as all censorship is
not necessarily wrong.