Baïkal : Baïkal offers ubiquitous and synchronized access to your calendars and address books over CalDAV and CardDAV. Baïkal implements the current IETF recom...
pump.io : Social server with an ActivityStreams API. It's a stream server that does most of what people really want from a social network.
YunoHost : YunoHost is a server operating system aiming to make self-hosting accessible to everyone.
Postal : Postal is a complete and fully featured mail server for use by websites & web servers. Think Sendgrid, Mailgun or Postmark but open source and ready f...
The Radicale Project is a complete CalDAV (calendar) and CardDAV (contact) server solution.