DAVdroid is one of the very rare Android CardDAV apps which have advanced support for vCard4. This means that (if your server supports it – for instance, KolabNow and Baïkal do) you gain

  • native contact group support (KIND/MEMBER) without hacks
  • native support for various properties (BDAY, IMPP, etc.)
  • no more charset problems (vCard 4 is always UTF-8)

DAVdroid

  • automatically detects whether vCard 4 is supported by the server (fallback: vCard 3)
    • detected by querying CARDDAV:supported-address-data property
  • uses vCard 4 for uploading and downloading contacts:
    • GET with Accept: text/vcard;version=4.0
    • CARDDDAV:addressbook-multiget with <address-data content-type='text/vcard' version='4.0'/>
    • PUT with Content-Type: text/vcard;version=4.0

Sample vCard 4:
0_1471964003962_vcard4.png
(red: some vCard4-specific properties)