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Web Calendar Servers
Calcium and iCal are both web calendar products. Once the software is installed on a single host computer, any number of users can point their web browsers to the system to view, edit, and manage the calendars.
Calcium has more features than iCal, and can be installed on almost any server. iCal is Windows-only - of course, users can access it from any kind of computer - and has its own built-in web server.
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Calcium vs iCal
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Architectural Differences
  • Perl CGI program (comes with Perl source code)
  • Runs under control of an existing web server (e.g. Apache, IIS and others)
  • Runs on any machine, including remotely hosted sites
  • Microsoft Windows executable program
  • Has a built-in web server
  • Runs on all Microsoft Windows platforms (but no other operating systems)

Feature Differences

Calcium and iCal are both rich in features. Both can merge data from multiple calendars, synchronize data with Outlook and Palm devices, provide a variety of calendar views, send email notifications and reminders, as well as support user defineable custom fields, different languages, iCalendar data exchange, RSS feeds and all of the other commonly expected features.

However, Calcium has more features than iCal; and in many cases where the two products have the same feature, Calcium will provide more options and flexibility. Calcium has been designed for the highest requirements, with features such as support for per-user security, time zones, secure socket connections, and LDAP authentication.

These are features and options provided by Calcium, but not iCal:

  • User Security Accounts: Calcium has user login accounts that provide a number of features throughout the system. A login account can be assigned specific access rights to individual calendars. For example, a user can have Administration rights for some calendars, edit rights to some others, and view-only rights to others. User accounts also allow for:
    • accurate auditing, such as who made changes to a calendar and when they were made
    • letting users post events to a common calendar, but allowing only the user who created an event to modify it
    • user management using User Groups; e.g. an administrative group could be given edit rights to a newly created calendar. Then, every user in that group would have these rights.
  • Secure Socket Connections: If your web server provides HTTPS, access to Calcium calendars will also be secure, since Calcium runs under control of the web server. (iCal's built-in server does not support HTTPS.)
  • Time Zone Support: Different users can view the same calendar using different time zones. For example, if a person in New York adds an event scheduled for 1pm, a user viewing that calendar from San Francisco would see the time for the same event displayed as 10am. Each user can have their own time zone offset setting.
  • LDAP / Active Directory support: You can choose to authenticate users against your existing LDAP directory; you still have the option to create and use Calcium's built-in user logins at the same time.
  • Multiple categories per event: Both iCal and Calcium allow specifying a category for an event. However, Calcium allows an event to have any number of categories assigned, while iCal supports just one. This provides for more sophisticated filter views of a calendar, as well as more flexibility when including events from other calendars by category.
  • More recurring event options: Calcium has additional options for repeating events, such as repeating every 5th, 6th, 7th, ... week, repeat on the 5th week of the month if it exists, repeat ever other month, every 2nd month .... every 6th month.
  • Defined Time Periods: Time periods allow you to assign names to time ranges. E.g. 8:00 am to 9:15 am could be defined as Class Period One. When an event as added to the calendar this name could be selected rather than specific time assignments.
  • Time Increments: in Calcium, event times can be assigned down to the minute. The minimum time increment in iCal is 5 minutes.
  • Event Sorting: iCal can display events in a day sorted alphabetically by text or by time. Calcium has options to sort alphabetically, time, category or by included calendar. Calcium also provides secondary sorting.
  • Additional Calendar Views: Calcium provides Quarterly and Fiscal data views.
  • And More: There are many other extras in Calcium, included email aliases, more font and color assignments, better CSS control, more RSS options, etc.

You can download fully functional copies of both programs to try at no charge. The demonstration downloads are limited to a single calendar, but they'll allow you to determine which product is right for your environment.
You can also try a multiple-calendar version of Calcium by setting up a free, private trial that runs on our servers:

Pricing depends on the number of calendars you need; all versions of iCal and Calcium support any number of users.