psi: Psi (Jabber client) psi: psi: Psi is the premiere Instant Messaging application designed for psi: Microsoft Windows, Apple Mac OS X and GNU/Linux. Built upon an open psi: protocol named Jabber, Psi is a fast and lightweight messaging client psi: that utilises the best in open source technologies. psi: psi: For more information, see http://psi.affinix.com/ psi: psi: psi: