DAVx⁵ is an open-source CalDAV/CardDAV suite and sync app for Android. You can also access your online files (WebDAV) with it.

GNU General Public License v3.0

davx5-ose

xandikos

A simple CalDAV (calendar) and CardDAV (contact) server.

Radicale

🦄 A modern web client for SFTP, S3, FTP, WebDAV, Git, Minio, LDAP, CalDAV, CardDAV, Mysql, Backblaze, ...

GNU Affero General Public License v3.0

filestash

sabre/dav is a CalDAV, CardDAV and WebDAV framework for PHP

BSD 3-Clause "New" or "Revised" License

SOGo is a very fast and scalable modern collaboration suite (groupware). It offers calendaring, address book management, and a full-featured Webmail client along with resource sharing and permission handling. It also makes use of documented standards (IMAP, CalDAV, CardDAV, etc.) and thereby provides native connectivity (without plugins) to many clients such as Microsoft Outlook, Apple iCal, the iPhone, Mozilla Lightning, and a plethora of mobile devices.

davx5-ose

xandikos

Radicale

filestash

dav

sogo