ejabberd

ejabberd is a multi-platform, scalable, distributed, and fault-tolerant Jabber/XMPP server. It includes Jabber services like Multi-User Chat, IRC transport, HTTP-Bind, Publish-Subscribe and PEP. It supports virtual hosting, connection to transports (gateways) to other networks, and connection to other Jabber servers. Other supported features are Web and command-line administration, encryption support (SSL and TLS), several authentication methods (embedded, external script, LDAP, PAM, and ODBC), varied storage methods (embedded, ODBC, PostgreSQL, MySQL, MSSQL), Jabber user directory, and translations in more than 20 languages.