Vivaldi

DAVx⁵ has been successfully tested with web.de.

Vivaldi is a privacy and data-sensitive web browser. It also offers many other services like address books and calendars.

DAVx⁵ settings

CalDAV Base URL: https://calendar.vivaldi.net/calendars/<USER@vivaldi.net>/default/ (where /default/ is the name of your calendar and <USER@vivaldi.net> is your login email address)

CardDAV Base URL: https://calendar.vivaldi.net/addressbooks/<USER@vivaldi.net>/default/ (where /default/ is the name of your address book and <USER@vivaldi.net> is your login email address)

Contact group method: groups are separate VCards (or the method used by your other clients)

Important: Please do not use the vivaldi.net web interface to create or edit calendar events. Currently there are some issues with recurring events and exceptions of recurring events.

Instead use vivaldis extra apps and the desktop client that is available for all operating systems.

Managing contacts in the web interface should work fine.