Mac
 * MSN Messenger
 * Psi
 * QQ
 * Skype
 * Windows Messenger
 * Yahoo! Messenger
Other
 * Akeni
 * BitWise IM
 * FotoSwap
 * Gadu-Gadu
 * Gossip Corporate Messenger
 * Instan-t
 * LanTalk NET Corporate Messenger
 * LanTalk XP LAN Messenger
 * Lotus Sametime
 * My Messenger
 * Omnipod
 * Sonork
 * talk
 * TiVi
 * Tlen
 * Xfire
Multi-protocol
 * Adium
 * Agile Messenger
 * aMSN
 * Ayttm
 * BitlBee
 * BlowSearch Secure Messenger
 * Centericq
 * Colloquy
 * Easy message
 * Everybuddy
 * Fire
 * Gaim
 * Hello
 * InstantCharts
 * iChat
 * IM2
 * IMVITE Video/Audio/Multi-chat
 * Konnekt
 * Kopete
 * Milkbone
 * Meetro
 * Miranda IM
 * naim
 * ngIM Client
 * Odigo Messenger
 * Proteus
 * Regnessem
 * Qnext
 * SIM
 * Trillian
 * Yamigo (for mobile phones)
Single protocol
 * Kadu
 * Licq
 * mICQ
 * Sticker
 * Trele Morele
Jabber protocol
 * Coccinella
 * Exodus
 * Google Talk
 * Gabber
 * Gajim
 * JAJC
 * Psi
 * Tkabber