Extensible Messaging and Presence Protocol

Extensible Messaging and Presence Protocol (XMPP) (formerly named Jabber)

Kliyenteng XMPP 
 Akeni Jabber Client (Cross-platform, proprietary (free for non-commercial use)) http://www.akeni.com 
 BellSouth Messenger (Windows, proprietary) (free for BellSouth Internet Service Customers)
 Bombus (J2ME/MIDP2.0, free) http://bombus.jrudevels.org/
 cabber (Cross-platform, GPL) http://cabber.sourceforge.net/ (text mode interface, outdated)
 Chatopus (PalmOS, proprietary) http://www.chatopus.com/
 Coccinella (Windows/Mac OS X/Linux/Unix, GPL) http://hem.fyristorg.com/matben/ 
 Colibry IM (J2ME/MIDP, free) http://violonix.com/
 Exodus (Windows, GPL)
 Gabber (Linux/Unix, GNOME, GPL)
 Gajim (Cross-platform, GPL) http://www.gajim.org/
 GOIM (Cross-platform, GPL) http://goim.sphene.net/
 Gossip (Linux/Unix, GNOME, GPL) http://developer.imendio.com/wiki/Gossip 
 Gush (Linux/Mac OS X/Windows, Creative Commons) http://2entwine.com/ 
 Iruka (Cross-platform, GPL) http://www.nongnu.org/iruka/ (outdated)
 jabber.el (Emacs-Lisp, GPL) http://sourceforge.net/projects/emacs-jabber (Emacs interface)
 JabberFoX (Mac OS X, BSD license) http://jabberfox.sourceforge.net
 Jabberzilla (Cross-platform, MPL/GPL/LGPL) http://jabberzilla.jabberstudio.org/ 
 Jabber Messenger (Windows, proprietary) http://www.jabber.com 
 Jabber WindowGram Client (Mac OS X/Linux/Unix, GPL) http://jwgc.blathersource.org/  (text mode interface)
 JAJC (Windows, proprietary, but free for any use)
 JBother (Java, GPL) http://jbother.org/
 Jeti (Java, GPL) http://jeti.jabberstudio.org/ 
 Jeti/2 (Java/eComStaton/OS/2, GPL) http://www.ehlertronic.de/jeti2.htm 
 mcabber (Cross-platform, GPL) http://www.lilotux.net/~mikael/mcabber/ (text mode interface, forked from cabber)
 moJab (J2ME/MIDP, GPL) http://mojab.sf.net/
 Neos (Windows, proprietary) http://www.neosmt.com/
 Nitro (Mac OS X, GPL) http://nitro.jabberstudio.org/ 
 Pandion (Windows, proprietary) http://www.pandion.be/
 Psi (Cross-platform, GPL) http://psi.affinix.com/ 
 sjabber (Cross-platform, GPL) http://www.pipetree.com/jabber/sjabber/  (text mode interface, outdated)
 TipicIM (Windows, proprietary) http://www.tipic.com/
 TipicME (J2ME-PersonalJava, proprietary) http://www.tipic.com/
 TipicWeb (JavaApplet, proprietary) http://www.tipic.com/
 Tkabber (Cross-platform, GPL) http://tkabber.jabber.ru/
 TSIM (Windows, proprietary) http://triplesoftware.nl/
 Whisper IM (Java, Creative Commons) https://whisperim.dev.java.net/ 
 JWChat (JavaScript, GPL) http://jwchat.sourceforge.net/ 
 Freetalk (Linux/Unix,GPL) http://savannah.nongnu.org/projects/freetalk/

Pangrehiyong Komunidad 
 JabberAfrica (Africa) - http://www.jabberafrica.org/ 
 Jabber.org.au (Australia) - http://www.jabber.org.au/ 
 Jabber.cz (Czech Republic) - http://www.jabber.cz/
 JabberFR (Pransiya) - http://www.jabberfr.org/
 Amessage (Aleman/International) - http://web.amessage.info/ 
 Jabber.or.id (Indonesia) - http://www.jabber.or.id/ 
 Jabber.ro (Romania)- http://www.jabber.ro/ 
 Jabber.ru (Russia) - http://www.jabber.ru/
 JabberES (Espanya) - http://www.jabberes.org/
 JabberPL (Poland) - http://www.jabberpl.org/ 
 Jabber Norge (Norway) - http://www.jabber.no/ 
 Jabber.dk (Denmark) - http://www.jabber.dk/

XMPP Server Software 
 Antepo OPN (Java, commercial) http://www.antepo.com/?products.opnserver
 chime (Java, GPL) http://www.codecobra.com/chime/  (doesn't have S2S support  yet)
 ejabberd (Cross-platform, GPL) http://ejabberd.jabber.ru/ 
 Jabber XCP (Linux/Solaris/Windows, commercial) http://www.jabber.com/ 
 jabberd (Cross-platform, GPL) http://jabberd.jabberstudio.org 
 jabberd2 (Cross-platform, GPL) http://jabberd.jabberstudio.org/2/ 
 Jive Messenger (Java, GPL) http://www.jivesoftware.org 
 Merak IM (Windows, commercial) http://www.icewarp.com/products/instant_messaging/
 Tigase (Java, GPL) http://www.tigase.org/
 TIMP.NET (Windows, commercial) http://www.tipic.com/
 xmppd.py (Cross-platform, GPL) http://sf.net/projects/xmpppy/

References

Kawing Panlabas 
 XMPP Standards Foundation
 XMPP Extensions
 XMPP Software: Clients
 XMPP Software: Servers
 Public XMPP Services
 Jabber.org (Free XMPP server of the XSF

Software