Alternatives to bIRC for all platforms with any license

Thunderbird

Thunderbird is a free, open source, cross-platform e-mail, news and instant messaging client. The project strategy is modeled after Mozilla Firefox.

Free Open Source Mac Windows Linux BSD PortableApps.com ... Haiku
Extensible by Plugins/Extensions Support for IMAP Built-in RSS reader Encryption ... SMTP integration Add-ons Calendar integration Extensions Multiple Account support Protected by Password Tabs Built-in Calendar Categories Customizable Delivery reports Extensible by Plugins/Extensions Free API Gmail integration Google Calendar integration Import from Google Reader Gui HTML Compose Integrated Chat Integrated Password Manager Integrated Web Browser Intuitive Legacy addons support Export to OPML Import feeds from OPML Organize mails POP3 Support Portable Secure File Sharing Support for POP3 Tabbed interface Support for Themes Add a feature

2004 Like
Pidgin

Pidgin is an easy to use, multi-protocol chat client client used by millions. Connect to AIM, MSN, Yahoo, XMPP, and more chat networks all at once. It has built-in...

Free Open Source Mac Windows Linux BSD PortableApps.com ... Xfce
Support for Multiple protocols Support for Multiple protocols Extensible by Plugins/Extensions IRC ... Plugins Supports XMPP Chat Messaging Multiple languages Multiple Account support Multiple chat protocols Portable Video calling Voice Call Xmpp Add a feature

1474 Like
HexChat

HexChat is an IRC client based on XChat for Linux , but unlike XChat it’s completely free for both Windows and Unix-like systems. HexChat was...

Free Open Source Mac Windows Linux BSD PortableApps.com ... Xfce MacPorts XQuartz
IRC Portable Add a feature

194 Like
mIRC

mIRC is a popular Internet Relay Chat client used by millions of people, and thousands of organizations, to communicate, share, play and work with each other on IRC...

Commercial $ $ $ Windows
Chat Colored Text IRC Add a feature

88 Like
Quassel IRC

Quassel IRC is a modern, cross-platform, distributed IRC client based on the Qt4 framework. Distributed means that one (or multiple) client(s) can attach to and detach...

Free Open Source Mac Windows Linux Self-Hosted
Chat IRC QT Based Standalone Add a feature

45 Like
irssi

Irssi is a terminal based IRC client for UNIX systems. It also supports SILC and ICB protocols via plugins.

Free Open Source Mac Windows Linux BSD Cygwin
Chat Add a feature

77 Like
KVIrc

KVIrc is a free portable IRC client based on the excellent Qt GUI toolkit. KVirc is being written by Szymon Stefanek and the KVIrc Development Team with the contribution...

Free Open Source Mac Windows Linux BSD PortableApps.com
Chat IRC Portable Add a feature

40 Like
WeeChat

WeeChat is a fast, light and extensible chat client. It runs on many platforms (including Linux, BSD and Mac OS). WeeChat is: - modular: a lightweight core with...

Free Open Source Mac Linux Android BSD Xfce
Chat Command line interface Extensible by Plugins/Extensions IRC ... Modular System Support for Multiple protocols Xmpp Add a feature

32 Like
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XChat for Linux

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...
- Discontinued
  The program is no longer updated. Last version, 2.8.8, released in May 2010, can be still downloaded from the official website.
Free Open Source Windows Linux
Chat IRC Add a feature

102 Like
Kiwi IRC

A hand-crafted IRC client that you can enjoy. Designed to be used easily and freely. More friendly than other webirc clients giving the general public an easy option to...

Free Open Source Web Self-Hosted Chrome
Chat IRC Preconfigurable auto-connect Add a feature

22 Like