CalView is a React-based calendar that integrates with a Radicale CalDAV server. It allows users to view, create, edit, and delete events, all synchronized with a Radicale backend. Has all of the features you'd expect of an online calendar.
A CalDAV, CardDAV and WebDAV framework for PHP. Supports PHP v7 at a minimum. Fully supports a large number of standards for calendaring, contact management, and more. Will work with both Apache and Nginx. Requires Composer to build (because of course you have to compile PHP apps these days).
While some web servers implement *DAV natively (like Apache), this code implements them itself without needing that underlying support. A very simple WebDAV server in PHP is provided as a PoC.
Nice to know that it's an option, but if there are better ones out there, those are probably preferable.
VObject is intended to be a full-featured Python package for parsing and generating vCard and vCalendar files. vCard 3.0 files are supported.
Simple command-line CalDav client, for adding and browsing calendar items, todo list items...
Github repo for this module: https://github.com/python-caldav/caldav
The Debian project's canonical list of groupware available for Debian.