mIRC, HexChat, SeaMonkey, Quassel IRC, KVIrc, ZeroChat, Kiwi IRC, irc.lc, XChat for Linux, Mibbit, Colloquy, IRCCloud, irssi, Konversation, AdiIRC, IRCAnywhere, Linkinus, PChat-IRC, ClicksAndWhistles, AmIRC, wsIRC, HydraIRC, Floe, MIRGGI, MacIrssi are some alternatives to Chatzilla.