Wikipedia:IRC/Clients

• Web clients
  • IRCCloud (website)
  • KiwiIRC (website)
• Most desktop operating systems (including Windows, macOS, and Linux/*nix)
  • ChatZilla (website; requires SeaMonkey)
  • HexChat (website, unmaintained)
  • irssi (website; text-based user interface, runs in your terminal)
  • Pidgin (website)
  • WeeChat (website; text-based interface)
• Windows only
  • AdiIRC (website; freeware)
  • mIRC (website; shareware)
• macOS only
  • Adium (website)
  • Colloquy (website)
• Mobile IRC clients
  • Colloquy (Apple App store)
  • IRCCloud (Apple App store, Google Play store)