MongooseIM platform

Tigase Jabber/XMPP Server   (Compare Project)

Mostly written in Java

License: AGPL3_or_later

miniim   (Compare Project)

Mostly written in Java

License: gpl3_or_later

Strophe.js   (Compare Project)

Mostly written in JavaScript

License: mit

Kamailio (SIP Express Router)   (Compare Project)

Mostly written in C

License: gpl

Openfire   (Compare Project)

Mostly written in Java

License: apache_2

ejabberd   (Compare Project)

Mostly written in Erlang

License: gpl

Dimdim   (Compare Project)

License: mozilla_public_1_1

Pandion NG   (Compare Project)

Mostly written in JavaScript

License: gpl3

CappuccinoTalk   (Compare Project)

Mostly written in Objective-J

License: lgpl-2_0

Ubiety   (Compare Project)

Mostly written in C#

License: lgpl3