Citadel is an advanced messaging and collaboration system for groupware and BBS applications. Users can connect to Citadel using any telnet, WWW, or client software. Among the features supported are public and private message bases (rooms), electronic mail, real-time chat, paging, shared calendaring, address books, mailing lists, and more. Unlike other collaboration servers, Citadel provides its own data stores and is therefore extremely easy to install; you don't have to "bring your own" email and database because they're built in. The server is multithreaded and scalable. In addition, SMTP, IMAP, and POP3 servers are built-in for easy connection to Internet mail. Citadel is both robust and mature; it has been in production since 1987.
E*Reminders is a series of PHP scripts that interact with a MySQL database to setup email reminders for any events or occasions you'd like. It includes recurring reminders, advance notices, and password authentication for email addresses. It can be used for an entire company, as a service for Internet users on your site, or privately.
phpGroupWare (formerly known as webdistro) is a multi-user groupware suite written in PHP. Its provides a Web-based calendar, todo-list, addressbook, email, news headlines, and a file manager. The calendar supports repeating events. The email system supports inline graphics and file attachments. The system as a whole supports user preferences, themes, user permissions, multi-language support, an advanced API, and user groups.
OpenGroupware.org is a set of applications for contact, appointment, project, and content management. It is comparable to Exchange and SharePoint. It is accessible using Web interfaces or using local clients via WebDAV, GroupDAV, and CalDAV. Custom applications can be developed using the XML-RPC API. OpenGroupware.org runs on almost every GNU/Linux system.
NullLogic Groupware is a modular Web-based groupware and email system designed for contact management and event scheduling. Additional features include private messaging, public discussion forums, webmail, shared bookmarks, file sharing, call tracking, order processing, an XML-RPC API, and integrated POP3 and SMTP servers.
MyPhPim contains a Web-based email client, todo list, notes app, addressbook, and calendar. Future goals include features for Palm Pilot syncing and file storage. MyPhPim is multi-user, so you can share your records with other users and/or other groups. Multiple mailboxes for each user can be defined. MyPhPim requires MySQL, and PHP4 with IMAP, MySQL, mcrypt, and socket support.
Share360 is an instant, cost-effective Web-based groupware suite integrating a customizable intranet portal page with key collaborative applications including document management, project management, contact databases, a group scheduler, a bulletin board, a to-do list, Web-based email, and Outlook Sync for Address Book. A 60-day free trial download is available.
Twiggi Web Based Groupware is a Web based groupware application, written in PHP4, using MySQL as its database engine. It was originally based on the excellent TWIG project. With many on-going enhancements, it is similar to Microsoft Outlook, and features the following modules: twiggi today, Mail, Contacts, Notes, ToDo, Bookmarks, and extensive online help (available in English and German). Twiggi has full language support for German, Dutch, Italian, and English.