Web Calendar Access Protocol (WCAP) is a protocol for remote client-server calendar access and scheduling based on the XML, HTTP, iCalendar, and vCard Internet standards.
WCAP was created for use with the product that eventually became Sun Java System Calendar Server. WCAP uses simple HTTP GET commands for accessing iCalendar, Freebusy, TODO and vCard entries. WCAP responses are either the traditional text form or an XML form of iCalendar/etc.[1] Several plugins exist including those for Mozilla Thunderbird,[2] Novell Evolution[3] and Microsoft Outlook.[4]
CalDAV is a competing protocol which as of 2007 underwent standardization.[citation needed]