A universal instant messaging (IM) program
See https://pidgin.im/about/ for more information. Pidgin is an instant messaging program which lets you log in to accounts on multiple chat networks simultaneously. It runs on Windows, Linux, and other UNIX operating systems. Pidgin is compatible with the following chat networks out of the box: AIM, ICQ, Google Talk, Jabber/XMPP, MSN Messenger, Yahoo!, Bonjour, Gadu-Gadu, IRC, MXit, Novell GroupWise Messenger, Lotus Sametime, SILC, SIMPLE, MySpaceIM, and Zephyr. It is written in C and makes heavy use of GLib and GTK+. Finch is a command line instant messaging program. It also lets you log in to accounts on multiple chat network simultaneously, and it is compatible with the same chat networks as Pidgin. It is written in C and makes heavy use of GLib and ncurses.
A smaller, faster, and easier IM client
Miranda IM is an open source, multi-protocol instant messaging client designed to be very light on system resources, extremely fast and customizable. A powerful plugin-based architecture make Miranda IM one of the most flexible clients on the planet.
Encryption plugin for Pidgin, providing up to 4096 bit RSA encryption using the NSS crypto library from Mozilla. Keys are automatically transmitted and stored, making it very easy to use, but also resistant to man-in-the-middle attacks.
A multi-protocol instant messaging app for Mac OS X
Adium is an Open Source, multi-protocol instant messaging application for Mac OS X. Adium supports AIM, ICQ, Jabber, MSN, Yahoo!, Google Talk, Bonjour, Gadu-Gadu, Novell Groupwise, SIP/SIMPLE (Text), and Lotus Sametime. Additionally, it supports all of these applications at once so, even if you have multiple IM accounts, you don't have to log into each account separately.
Chat on Facebook without going to the site !
Login to your facebook chat with ease, you can hide the program to tray icon so it doesn't annoy you, it will run and won't slow your PC down no matter if you are rendering a HD video, or playing a high-end PC game. ;)
Bot Sentry is a Pidgin (libpurple) plugin to prevent Instant Message (IM) spam. It allows you to ignore IMs unless the sender is in your Buddy List, the sender is in your Allow List, or the sender correctly answers a question you have predefined.
pork, oidentd, iplog and ocd
Licq is an ICQ/AIM clone written fully in C++. It uses an extensive plugin system to manage many different functions including the MSN protocol. The main GUI is written using the Qt widget set.
Gabber is an easy yet powerful Jabber client for GNOME. Jabber is a powerful open source instant messaging system. Jabber allows communication with other networks, such as ICQ, AIM, MSN, Yahoo, and even IRC, but beyond that it has unique features of its
Fire is a multi-protocol instant messenger client for Mac OS X based on freely available libraries for each service. Currently Fire handles AOL Instant Messenger®, ICQ®, MSN® Messenger, Jabber, limited IRC, Yahoo!®, and Apple Bonjour communications.
JAIMBot is a modular architecture for providing services through an AIM client. It contains a generic AIM library and a Bot which uses this library to provide such services as Offline Messaging, Lists, Weather, Headlines, Stock Quotes, AI chatterbot.
A fork of pidgin which aims to provide minor features that have not been addressed by the pidgin development team (including manual textbox resizing). See funpidgin.sf.net for details.
This is an unofficial native port of Pidgin to Mac OS X. It uses native GTK+ (www.gtk-osx.org) which provides better integration and does not require X11. It also comes with more plugins out of the box, including OTR.
Pidgin Extended Preferences provides additional preferences for Pidgin users. Most notably, it allows you to change the font size of conversation text without changing your theme and to change how quickly or whether the buddy list tooltips appear.
A pidgin plugin that allows user to assign global hotkeys (e.g. Ctrl+Alt+g) for togglling buddy list and reading queued message. When "Toggle List" hotkey is enabled, it makes the buddy list hidden from your taskbar and task switcher (similar to ICQ).
Kraken is a continuation of the Openfire IM Gateway plugin, but in a way that works for any XMPP server. It provides a way for XMPP users to log into, and communicate through, their legacy IM accounts such as AIM, ICQ, MSN, Yahoo, and friends.
Multiprotocol plugin-based instant messenger for X11 (optionaly support KDE), Windows and MaxOS X.
Intercepts and parses all instant message traffic received by the computer. A high performance engine allows conversations to be viewed immediately and/or saved for later analysis. NOTE: Requires WINPCAP
This project provides a basic Java implementation of the OSCAR protocol, used by ICQ and AIM clients. Commonly used features such as messaging, status and server buddy lists are supported, making it easy for developers to use this in their own work.
A free Win32 instant messaging client. Smaller, Faster, Easier.
Send XMPP (Gtalk/Google Talk also supported) messages (thanks to Jabber) within a single line of PL/SQL code, get buddies list and status in relational tables (or xml) on Oracle 11g.
A graphical notification plugin for the instant message client gaim. Now hosted at http://plugins.guifications.org/trac
TiK is an open source AOL IM client written in tcl and very portable. It was originally developed as an alternative to java AIM for UNIX users. Sadly, this project seems to have been abandoned by AOL. This site will be used for further development of Tik.
Line-based AIM client and BSD-licensed OSCAR library.
Kopete is a flexible and extendable multiple protocol instant messaging system designed as a plugin-based system.