PuTTY - Popular free terminal application. Mostly used as an SSH client.
HexChat - HexChat is a fork of XChat with bug fixes and new features.
MobaXterm - Enhanced terminal for Windows with X11 server, tabbed SSH client, network tools and much more
irssi - Irssi is a terminal based IRC client for UNIX systems.
iTerm2 - A terminal emulator for macOS that does amazing things.
Kiwi IRC - A hand-crafted IRC client that you can enjoy. Designed to be used easily and freely.