CalDavZAP is an open source, platform-independent and completely free web-based application designed to act as an online CalDAV client, supported on Mozilla Firefox, Google Chrome, Epiphany, Webkit, iCab, Opera and Safari/Mobile Safari web browsers. It is written in JavaScript and jQuery, and it does not require any special server software for a standard setup, except for the CalDAV server, of course.

Key features include server-based XML configuration generator with LDAP and HTTP authentication plugins, asynchronous read-only, as well as read and write calendar collection detection, asynchronous background synchronization, support for RFC compliant vCalendars, support for subscribed calendars and delegated calendars, and support for background calendars.

The application also provides read and write support for standard vCalendar components, such as VEVENT, VALARM, VTIMEZONE and VTODO, as well as for a wide range of standard vCalendar attributes, including DTEND, DTSTART, SUMMARY, RRULE, DESCRIPTION, LAST-MODIFIED, DUE, CREATED, RECURRENCE-ID, TRIGGER, EXDATE, ACTION, PERCENT-COMPLETE, STATUS, UID, TZOFFSETFROM, VERSION, TZOFFSETTO, CLASS, TRANSP, URL, and DURATION.

Another interesting feature is the ability to automatically correct most common issues in corrupted vCalendars. It provides support for time-range filtering if the server supports it, support for subscribed and delegated calendars, support for background calendars, automatic software updates, and support for numerous languages, including English, German, French, Danish, Czech, Slovak, Spanish, Russian, Turkish, Italian and Ukrainian.

In addition to the above, the CalDavZAP application offers a clean web-based user interface that features SVG graphics and allows users to move events using drag and drop. It also provides users with a very useful "select for add new event" functionality and full support for IANA timezone. The software is available for download as a universal ZIP archive, which can be easily deployed on any server machine powered by a GNU/Linux system.