CalDAV server implementation
supported implementation
Apple iCal Server
Commercial macOS Server, also Open source/cross-platform
Implementation of CalDAV Access and Scheduling. Available as part of the macOS Server software. Also open source. Python-based.
Bynari Collaboration Suite
Commercial Collaboration Suite
BCS (Bynari Collaboration Suite) is a complete groupware/messaging suite which includes CalDAV support.
Baïkal
Open Source
Baïkal is a Cal and CardDAV server, based on sabre/dav.
Bedework
Open source/cross-platform
Implementation of CalDAV Access and Scheduling. Java-based. Includes a Web UI.
Chandler Server (Cosmo)
Open Source
Java-based server that includes support for CalDAV. Created from the chandler project, now supported by 1&1
Communigate Pro
Commercial
Implementation of CalDAV Access and Scheduling as part of unified messaging server.
DAVical
Open Source/PHP/PostgreSQL
Implementation of CalDAV Access and Scheduling with web-based administration.
DPCalendar
GPL/Joomla
DPCalendar allows CalDAV access to its event system on your Joomla site.
DavMail
Open Source/Java
DavMail is a POP/IMAP/SMTP/Caldav/LDAP exchange gateway allowing users to use any mail/calendar client with an Exchange server through Outlook Web Access.
Daylite CalDAV Server
Commercial CalDAV Server
Daylite is a commercial CalDAV server
EGroupware
Open Source/Commercial/Free Hosted Trial
EGroupware is an enterprise ready groupware server that includes CalDAV and CardDAV support.
EVO Mail Server
Shareware/Trial Period
CalDAV and CardDAV support.
Fennel
Open Source/JavaScript
Fennel is a lightweight CardDAV / CalDAV server. It is completely written in JavaScript and runs within a Node.js instance.
Kerio Connect
Commercial
Implementation of CalDAV Access and Scheduling as part of unified messaging server.
OX App Suite
Open Source/Commercial/Cross Platform
The number one open cloud service platform that provides open standard interfaces such as CalDAV/CardDAV/WebDAV/IMAP/PGP/… to all it services such as unified email, calendar, cloud storage, security, collaboration and much more.
Oracle Communications Calendar Server
Commercial
Implementation of CalDAV Access and Scheduling. Formerly Sun Java Calendar Server.
ownCloud
Open Source
ownCloud is an open source, simple cloud server, providing WebDAV, CalDAV, CardDAV, etc. It’s written in PHP and can use SQLite or MySQL databases. So it runs under Windows, Linux, etc.
Radicale
Open source / Cross platform
Radcale is an open source cross-platform CalDAV and CardDAV server written in Python. It requires few software dependencies and is pre-configured to work out-of-the-box.
sabre/dav
Open Source
SabreDAV is a free WebDAV server and includes support for CalDAV.
ScalableOGo
Open Source
ScalableOGo (SOGo) is a free groupware server and includes support for CalDAV.
Scalix
Commercial/Open Source
Implementation of CalDAV Access and Scheduling.
Zimbra
Commercial/Open Source
Implementation of CalDAV Access and Scheduling.
Xandikos
Open source/cross-platform
Xandikos is a lightweight free WebDAV server that includes support for CalDAV.
unsupported implementation
Dingo Calendar Server
Open Source/Perl/CGI
Dingo is a CalDAV compatible server using MySQL, written in Perl as a CGI script.
Status uncertain; appears to have been abandoned since 2008
ModCalDAV
Open source/cross-platform
Apache plugin implementing CalDAV Access.
Status uncertain; appears to have been abandoned since 2013
Synovel Collabsuite
Commercial/Linux
Synovel Collabsuite is an open source technology based mail and collaboration software. It provides comprehensive Linux mail server with calendaring (CalDAV) and instant messaging functionality for enterprise.
Status uncertain; appears to have been abandoned since 2009