Open source groupware with calendar, project management, request tracker and 12 other modules. Supports more than 16 languages. Requires mysql, oracle, postgres or informix db.

E-mail and collaboration software managed by Yahoo!. A server application as well as desktop and web based clients are available.

A servlet implementation of an open protocol GroupWare product. Backend (search engines, news, weather, POP3/IMAP/LDAP/NNTP, database) is based on other open source packages.

OpenACS (Open Architecture Community System) is an advanced toolkit for building scalable, community-oriented web applications.

onShore, a consulting firm, has a web-based, multi-user time-billing tool, GPL license.

A useful intranet/groupware tool and application framework. Written and implemented with PHP. Goal is to be a simple, cross-platform, fast way to access/share almost any kind of information, GPL license.

Groupware suite containing a base system and different modules including scheduler, email, file and projects. (PHP)

A multi-user web-based groupware suite written in PHP. It also provides an API for developing additional applications.

Free Open Source Portal Server allowing point and click community, content and XML syndication management on the Web, email, cellphone, other media.

A turnkey open source messaging and collaboration platform.