Pidgin (formerly named Gaim, and we can pronounce it "/ˈpɪdʒɪn/") is an open-source, cross-platform instant chat client application developed in GTK, supports all IM clients which using common instant communication protocols (see list below) at the same time.
Now in people's everyday life and work, we can't do without the network, and for network applications, instant messaging software play an important role. If your local area network (LAN) cannot be connected to the public network or not convenient to use ICQ, MSN such kind of IM applications that are already well known to everybody, then please use BORGChat, which can completely replace them perfectly.
IP Messenger is a widespread cross-platform LAN instant communication software; based on TCP/IP (UDP) protocol; no need the server system.
Miranda IM (short for Miranda Instant Message), an instant messenger designed only for Windows system, which is open source, supporting multiple protocol and customizable for many plugins, with very little system resources occupation.