Truly Cross Platform
All packages come with access to an plain white unrestricted CARDdav server, linked to email email@example.com.
Each email address can have unlimited Address Books and each Address Book can have sharing options set.
Online address book can be used simply to put all contacts on all your devices, on a add to one they all get that basis.
they can shared with selected/many/all email firstname.lastname@example.org and all devices can connect no hassle