CalDAV libraries
supported implementations
CalDAV4j
Open source/Java
CalDAV4j is a protocol library that extends the Slide project’s WebDAV client library (which itself is an extension of the Apache’s HttpClient library) to allow high level manipulation of CalDAV calendar collections as well as lower level CalDAV protocol interactions.
CalDAVClientLibrary
Open source/Python
A protocol library for CalDAV with an interactive shell.
caldav
Open source/Python
This project is a CalDAV (RFC4791) client library for Python.
iCal4j
Open source/Java
iCal4j is a Java library used to read and write iCalendar data streams as defined in RFC2445.
IT Hit WebDAV Server Engine for .NET
Commercial License
With IT Hit Engine you can add CalDAV and CardDAV support to your .NET web application in minutes using Visual Studio wizard. The IT Hit SDK is shipped with iCalendar and vCard parsing libraries covered by over 1500 unit tests and several C# template projects with Microsoft SQL and file system back-end storages that you can use as a starting point for CalDAV-enabling your CRM/CMS/ERP.
kcaldav
Open source/C
An open source library that is the basis for the CalDAV plugin currently under development for Kontact.
Libical
Open source/C
An open source reference implementation of the iCalendar data type and serialization format.
Milton
Java library
Milton is a java library for WebDAV, CalDAV and CardDAV server implementations.
pycalendar
Open source/Python
The library used by CalendarServer as part of its CalDAV/iCalendar support.
SOPE - OpenGroupware
Open source/Objective-C
The SOPE iCal package (sope-ical) contains a SaxObjC driver for processing iCalendar files using libical (iCalSaxDriver) and a library which contains model classes for iCalendar/vCard objects.
vdirsyncer
Open Source Command-Line Tool
vdirsyncer is a command-line tool to synchronize a CalDAV/CardDAV server with a local iCalendar/vCard file, or a folder of those. It can also be used to synchronize two DAV servers with each other.
vobject
Open source/Python
A Python library used to read and write iCalendar data streams as defined in RFC2445. Also does vCards. Now maintained by eventable.
unsupported implementations
kcaldav
Open source/C
An open source library that is the basis for the CalDAV plugin currently under development for Kontact.
This project is no longer being maintained.
Mulberry iCalendar Library
Open source/C++/Python/Java
The library used by the Mulberry client for its iCalendar and iTIP handling. Also includes Java and Python ports with similar APIs to the C++ one.
Not supported since 2005
RiCal
Open source/Ruby
Ruby library which provides parsing, generation, and usage of RFC 2445 (iCalendar) data, including support for enumerating occurrences of recurring components and time zone conversions.
Status uncertain; appears to have been abandoned since 2011