Calcium provides interactive calendars you can use through your browser. Features include: dynamic calendar merging (events from one calendar can be included in another), multiple views and formats, repeating events, email support, extensive color and font customization, support for full HTML in the event text and calendar headers and footers, popup text associated with any event, searching and filtering, multi-language support, a flexible security model, and more. Calcium is very easy to use, and fully supported by an established company. It runs anywhere that supports Perl CGIs; no non-standard Perl modules are necessary. Full 2-way synchronization with Palm Pilots or MS Outlook is available; iCalendar "subscriptions" are supported too.
CalCore is an advanced, flexible calendaring component for Python. It allows the Python developer to write advanced calendaring applications either using their own event storage or integrating with external calendar servers. It features support for private calendars, shared calendars, resource booking, integration with iCalendar clients (Apple iCal, Mozilla Sunbird, KOrganizer) using the iCalendar protocol, invitation workflow, meeting support, including helper functions to look for free time, and recurring event support. It is being used as the core of Nuxeo's CalZope and CPSSharedCalendar products.
Calcurse is a text-based calendar and scheduling application. It helps keep track of events, appointments, and everyday tasks. A configurable notification system reminds the user of upcoming deadlines, and the curses based interface can be customized to suit user needs. All of the commands are documented within an online help system.
CalendarTechnique is a Web-based calendaring and scheduling application. It lets you easily post, maintain, update, and archive calendar and scheduling entries such as events, tasks, and journal entries. It features displaying calendar entries in customizable day, week, month, year, or list layouts, extensive search and filtering capability (keyword search, field-specific search, date range search), support for the event, to-do/task, journal, and alarm components specified in the iCalendar specification, and a theme-based interface which allows you to preview and select any of the available themes (new themes can also be added and customized to match the look of an existing Web site).
Calendars for the Web provides a server based calendar and scheduling application. It allows unlimited users to share unlimted events per calendar. Calendars for the Web comes with a full-featured browser based interface, is completely customizable (sixteen different calendar view types), fully documented, and supports online administration.
Celebrat is a very easy-to-use, non-interactive, text-mode calendar application. It reads a data file in ASCII format, and prints on stdout a human-language summary of what events will take place up to ten days from now. It also includes a small daemon which announces events that are due by putting a message on every registered terminal, or by integrating the announcement in the bottom line of GNU screen sessions.
Chandler is a standards-based "Note-to-Self Organizer" designed for personal and small-group task management and calendaring. It consists of a desktop application and Chandler Hub, a free sharing service and Web application. You can also download and run your own Chandler Server.
Chronos is a Web agenda calendar for intranets, although it can be used from anywhere. It can send reminders by email, and it allows you to schedule multi-user events. It is fast and light on resources. The balance between size and speed can be tweaked by tweaking mod_perl and Apache.
Ciao is a complete Prolog system subsuming ISO-Prolog with a novel modular design which allows both restricting and extending the language. Ciao extensions currently include feature terms (records), higher-order, functions, constraints, objects, persistent predicates, a good base for distributed execution (agents), and concurrency. Libraries also support WWW programming, sockets, and external interfaces (C, Java, TCL/Tk, relational databases, etc.). An Emacs-based environment, a stand-alone compiler, and a toplevel shell are also provided.