The Integrated Groupware Suite, or IGSuite, is another Web-based open source groupware system. In addition to calendaring, e-mail, etc., it also incorporates some basic CRM, ERP and CMS functionality. Operating System: Windows, Linux, Unix.
Short for "The Ultimate Team Organization Software," includes group calendar, email, time tracking, document management and project management. In addition, it also offers special features for developers, like a bug tracker, test support and some Scrum tools . Operating System: Linux.
FileZilla comes in a server version that runs on Windows only, or a desktop client version that works on multiple platforms. In addition to regular FTP transfer, it also supports secure file transfer via FTPS or SFTP. Operating System: Windows, Linux, OS X
Award winning WinSCP offers a client for transferring files via SFTP, SCP, FTPS or FTP protocols. It includes two different interfaces: Explorer (which looks like Internet Explorer) and Commander (which looks like Norton Commander). Operating System: Windows
This add-on gives you an intuitive FTP client for the Firefox browser. It supports FTP or SFTP only. Operating System: Windows, Linux, OS X
This universal chat client allows you to IM with friends on numerous different networks, including AIM, ICQ, Google Talk, Jabber/XMPP, MSN Messenger, Yahoo, and others. It's available in dozens of languages, and numerous plug-ins extend its capabilities. Operating System: Windows, Linux/Unix
Pidgin doesn't work on a Mac, but this nearly identical app does. Operating System: OS X
Conceived as an MSN Messenger clone (before Microsoft changed the name to Windows Live Messenger), this app includes offline messaging, voice clips, photo support, custom emoticons and more. A large library of plug-ins and skins is also available on the site. Operating System: Windows, Linux, OS X
KDE's IM client supports AIM, ICQ, Windows Live Messenger, Yahoo, Jabber, Gadu-Gadu, Novell GroupWise Messenger and other networks. It also offers tools for archiving and encryption and a unique notification system that only lets "important" message through. Operating System: Linux
Small and fast, Miranda is very light on system resources. Like many of the other IM clients on our list, it supports multiple networks, including AIM, Facebook, ICQ, IRC, Yahoo and others. Operating System: Windows
The self-proclaimed "leader in open source e-mail and collaboration," Zimbra offers a mail server that provides an alternative to Exchange, as well as a desktop client that offers an alternative to Outlook. It's available in a variety of free and paid editions, including hosted versions and versions designed to run in a virtualized or private cloud environment. Operating System: Linux, Unix, OS X
This all-in-one platform combines a communications server with a security gateway, backup, network monitoring, infrastructure management, file server, Web server and more. In addition to the basic, free edition, it also comes in paid professional and enterprise versions, with other add-ons available as well. Operating System: Linux
Calling itself the "leader in true open source email and collaboration," Citadel features a unique "rooms" architecture that makes it versatile and flexible. It's available as a standard download, a VMware appliance or on a hosted basis. Operating System: Linux
Originally developed by IBM Research, Postfix is a secure mail transfer agent that is very similar to Sendmail (see below). It's fairly fast and can handle a large volume of mail. Operating System: Linux, Unix, OS X, Solaris