Miranda IM - (Open Source)
Miranda is a great instant messaging software, compatible with most existing software such as ICQ, AIM, MSN, Jabber, Yahoo, IRC, Gadu-Gadu, Tlen, Netsend.
Miranda is a very flexible instant messaging client for chatting on multiple networks simultaneously. It is able to connect to ICQ, AIM, MSN, Facebook, Jabber, Yahoo!, Gadu Gadu, IRC and some other protocols.
The purpose of software is to make this kind of communication as simple as possible. It is also possible to copy Miranda on a USB stick or other removable.
Miranda is also customizable with many other plugins and skins, and boasts a very active community.
Enhancements
# Support for multiple accounts (without dll renaming) for all protocols
# SSL support has been added to the core
# Support for compressed HTTP transactions
# AIM: Unicode messaging, status messages, profiles
# AIM: Offline messaging
# AIM: Set/retrieve status message for any status
# AIM: Ability to set your own avatar
# AIM: Privacy settings & lists support
# AIM: Server groups support
# AIM: Group Chat support
# AIM: SSL server connection support
# ICQ: Fixed receiving of multi-part messages (only first part was received)
# ICQ: Fixed processing of UTF-8 encoded status messages from QIP
# ICQ: New offline messages protocol (supports unicode)
# ICQ: New user details protocol support (fully unicode aware)
# ICQ: Added support for status notes & moods
# ICQ: URL events are now received as normal messages
# ICQ: Ability to send/receive contacts to/from ICQ6 and AIM
# ICQ: Server-list support now groups requests
# IRC: IRC servers now stored in the database
# IRC: Filter for IRC channel list
# IRC: Enhanced identd processing
# IRC: Added menu item for nickserv commands
# IRC: Auto request client info on adding to contacts or private message
# IRC: Enhanced WhoIs request
# IRC: CTCP events are shown in the server window
# IRC: Close windows with ESC button
# IRC: Quick Connect now allows manual input of server parameters
# Jabber: Bunch of new XMPP extensions implemented (XEPs: 70, 83, 108, 147, 184, 224, 232 and other)
# Jabber: Massive improvements in filetransfers
# Jabber: Improved GnuPG messages handling (using SecureIM/GPG plugins)
# Jabber: Localized server messages support (xml:lang, RFC 3920 section 4.4)
# Jabber: Server side notes (Miranda own extension)
# Jabber: Ability to invite chat users to another rooms
# Jabber: Directed presences, ability to change connection priority
# Jabber: Display active resource of user in message window
# Jabber: Jabber VCard moved integrated with user details
# Jabber: Redesigned almost all dialogs (roster editor, bookmarks, privacy lists, groupchat join, user info and other)
# Jabber: Redesigned menus (main menu in status bar, privacy lists menu, custom status, priority menu, groupchat menus and other)
# Jabber: Added new and updated old icons, improvements in UI
# Jabber: Added hotkeys and toolbar buttons
# Jabber: Options to auto-accept authorization requests and auto-reject invites to conferences
# Jabber: CTRL key shows disabled items in most menus
# Jabber: Various improvements in groupchats (show online status, improved topic and nick change dialogs and other)
# Jabber: Improved remote controlling (resources in forwarded messages, keep last options, leave groupchats)
# Jabber: Added display of quit messages, ability to send quit and slap messages
# Jabber: Use hostname as resource option
# Jabber: Improvements in XML Console (filters, formatting)
# Jabber: Ability to show jabber presence subscription states and errors
# MSN: Rewritten to support WLM 8.5 protocol (and all it features)
# MSN: Offline messaging
# MSN: Added Hotmail Notifier functionality
# Yahoo: Added Yahoo 9.x protocol support
# Yahoo: File transfer overhauled with support for batches of files
# Yahoo: Added user info dialog for Yahoo that shows more detailed information
# Yahoo: Improved support for HTTP proxies
# Yahoo: Yahoo Japan support
# Yahoo: Yahoo now provides a Unicode version
Bugfixes
# ICQ: Fixed receiving of multi-part messages (only first part was received)
# ICQ: Fixed processing of UTF-8 encoded status messages from QIP
# Jabber: Fixed various serious bugs (accidental account unregister, message sender spoofing, roster access by remote users)
# Jabber: Fixed wrong timestamps in offline and forwarded messages, fixed xmpp time answers
# Jabber: Various connection stability fixes (XMPP ping, ZLib keepalive and other)
# Jabber: Fixed chat issues with autojoin and unstable connection
# Jabber: Fixed displaying of active resource (including software info) in contact list
# Yahoo: Tons of bug fixes