Top Alternatives to mIRC

Pidgin is a free and open-source chat client which supports AIM, Google Talk, ICQ, XMPP protocols.

Miranda IM is an open source multiprotocol instant messaging application, designed for Microsoft Windows.

Empathy is an instant messaging (IM) and voice over IP (VoIP) client which supports text, voice, video, file transfers, and inter-application communication over various IM protocols.

HexChat is an open-source, cross-platform IRC client.

XChat is an IRC chat program for both Linux and Windows. It allows you to join multiple IRC channels (chat rooms) at the same time, talk publicly, private one-on-one conversations etc.

Irssi is an IRC client program for Linux, FreeBSD, Mac OS X and Microsoft Windows.

Quassel IRC, or Quassel, is a graphical, distributed, cross-platform IRC client.

Colloquy is a platform on loyalty, customer engagement and data analytics.

KVIrc is a graphical IRC client for Linux, Unix, Mac OS and Windows.

Smuxi is a cross-platform IRC client for the GNOME desktop inspired by Irssi.

WeeChat is a free and open-source Internet Relay Chat client, which is designed to be light and fast.

AdiIRC is a free Internet Relay Chat (IRC) client.

X-Chat 2 for Windows is an unofficial open-source GPL X-Chat (UNIX IRC client) build for Windows.

ZNC is an advanced IRC bouncer that is left connected so an IRC client can disconnect/reconnect without losing the chat session.

Konversation is an Internet Relay Chat (IRC) client built on the KDE Platform.

ChatZilla is an IRC client for Mozilla-based browsers such as Firefox.

KiwiI RC is a webIRC client.

Textual is an IRC client created specifically for macOS.

IRCCloud is a modern IRC client that keeps you connected.

LimeChat is an IRC client for Mac OS X.

Shout is a self-hosted web IRC client.

Mibbit is a fully featured IRC Client.