jabberd is the original Jabber/XMPP server developped by:
Jeremie Miller jeremie@jabber.org
Keith Minkler tsbandit@jabber.org
Thomas Muldowney temas@jabber.org
Schuyler Heath sheath@jabber.org
David Smith dizzyd@jabber.org
Matthias Wimmer m@tthias.eu
Maqi maqi@jabberstudio.org
There are now several implementations for XMPP servers. You can find a list of them on https://xmpp.org/software/servers.html
The source code of jabberd is available on GitLab and GitHub. You can get the source from both of these places, but please take note, that if you are interested in the integration test results, you have to check them on GitLab.
The home of jabberd is https://jabberd.org/.