CalDAV

Calendaring Extensions to WebDAV, or CalDAV, is an Internet standard allowing a client to access and manage calendar data along with the ability to schedule meetings with users on the same or on remote servers.[1][2] It lets multiple users in different locations to share, search and synchronize calendar data.[3] It extends the WebDAV (HTTP-based protocol for data manipulation) specification and uses the iCalendar format for the calendar data.[2] The access protocol is defined by RFC 4791.[1] Extensions to CalDAV for scheduling are standardized as RFC 6638.[1] The protocol is used by many important open-source applications.[3]