ZNC

Fast, light and extensible chat client.

Modular IRC server written in C++ for Linux, BSD, Windows, and macOS.

Portable and lightweight Internet Relay Chat server for small or private networks.

Distributed IRC client, meaning that one (or multiple) client(s) can attach to and detach from a central core.

Web IRC client.

Modern IRCv3 server written in Go, combining the features of an ircd, a services framework, and a bouncer.