GroupDAV is a computer protocol

Communications protocol

A communications protocol is a system of digital message formats and rules for exchanging those messages in or between computing systems and in telecommunications...

 used to connect Open Source

Open source

The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...

 groupware clients with Open Source groupware servers. It is a lightweight protocol whose primary design goal is to be as simple as possible to implement, focusing more on real world issues with open source applications than on an extremely extensive command set. It is based on a subset of WebDAV

WebDAV

Web-based Distributed Authoring and Versioning is a set of methods based on the Hypertext Transfer Protocol that facilitates collaboration between users in editing and managing documents and files stored on World Wide Web servers...

.

Client side GroupDAV implementations exist for KDE

KDE

KDE is an international free software community producing an integrated set of cross-platform applications designed to run on Linux, FreeBSD, Microsoft Windows, Solaris and Mac OS X systems...

 Kontact

Kontact

KMail supports folders, filtering, viewing HTML mail, and international character sets. It can handle IMAP, IMAP IDLE, dIMAP, POP3, and local mailboxes for incoming mail. It can send mail via SMTP or sendmail...

, Novell Evolution

Novell Evolution

Evolution or Novell Evolution is the official personal information manager and workgroup information management tool for GNOME. It combines e-mail, calendar, address book, and task list management functions. It has been an official part of GNOME since version 2.8 in September 2004...

, Thunderbird

Mozilla Thunderbird

Mozilla Thunderbird is a free, open source, cross-platform e-mail and news client developed by the Mozilla Foundation. The project strategy is modeled after Mozilla Firefox, a project aimed at creating a web browser...

 and Outlook

Microsoft Outlook

Microsoft Outlook is a personal information manager from Microsoft, available both as a separate application as well as a part of the Microsoft Office suite...

, work on the Mozilla Calendar Project

Mozilla Calendar Project

The Mozilla Calendar Project is the name for the Mozilla project that led to the development of Sunbird calendar application and the Lightning integrated calendar...

 is in progress. Servers include OpenGroupware.org

OpenGroupware.org

SOGo is an Open Source collaborative software server with a focus on simplicity and scalability...

, SOGo

Sogo

Sogo Co., Ltd. is a department store chain that operates an extensive network of branches in Japan. It once owned stores in locations as diverse as Beijing in China, Causeway Bay in Hong Kong, Taipei in Taiwan, Jakarta, Medan, Bandung & Surabaya in Indonesia, Kuala Lumpur in Malaysia, Singapore,...

, the Citadel

Citadel/UX

Citadel/UX is a collaboration suite that is descended from the Citadel family of programs which became popular in the 1980s and 1990s as a bulletin board system platform. It is designed to run on open source operating systems such as Linux or BSD...

 system and eGroupWare

EGroupWare

EGroupware is free open source groupware software intended for businesses from small to enterprises. Its primary functions allow users to manage contacts, appointments, projects and to-do lists....

. In addition every WebDAV

WebDAV

Web-based Distributed Authoring and Versioning is a set of methods based on the Hypertext Transfer Protocol that facilitates collaboration between users in editing and managing documents and files stored on World Wide Web servers...

 (and therefore CalDAV

CalDAV

Calendaring Extensions to WebDAV, or CalDAV, is an Internet standard allowing a client to access scheduling information on a remote server. It extends WebDAV specification and uses iCalendar format for the data. The protocol is defined by RFC 4791...

/CardDAV

CardDAV

CardDAV is an address book client/server protocol designed to allow users to access and share contact data on a server.The CardDAV protocol was developed by the IETF and has been published as RFC 6352....

) server is implicitly a GroupDAV v2 server.

GroupDAV's relationship to CalDAV

CalDAV

Calendaring Extensions to WebDAV, or CalDAV, is an Internet standard allowing a client to access scheduling information on a remote server. It extends WebDAV specification and uses iCalendar format for the data. The protocol is defined by RFC 4791...

varies from developer to developer. Some of the earliest implementors intended it as a protocol complementary to the CalDAV effort, because CalDAV provides more extensive operations on calendar folders. Others have positioned GroupDAV as the leading protocol, citing CalDAV's excessive complexity as a source of interoperability bugs. This dichotomy is likely to become irrelevant in the future, however, as it is straightforward for a server to simultaneously support both protocols.