Thabot is an alternative IRC bot for channel administration, developed by french people, written in C and working on several platforms including Windows and un*x systems. Its use is very simple, quick, with level and dynamic level user access, and more t
libircclient is a small but powerful library, which implements client-server IRC protocol. It has all features needed to create your own IRC client or bot, including multi-threading support, sync and async interfaces, CTCP/DCC support, colors, SSL connections and so on.
nwIRC is a small console IRC client for Unix systems. It works without third-party libraries and has been tested on Free/Net/OpenBSD, Darwin, Solaris, HP-UX, OSF1/Tru64, IRIX, AIX, Linux and Cygwin. Key features are multiserver/IPv6/DCC/modules support
psyBNC is an easy-to-use, multi-user, permanent IRC-Bouncer with many features. Some of its features include symmetric ciphering of talk and connections (Blowfish and IDEA) It compiles on Linux, FreeBSD, SunOs and Solaris.