ContactSync syncs your contacts with CardDAV, FTP, HTTP, WebDAV servers, Cloudstorage, or local files (stored on the device or e.g. as a mail attachment). A quick overview on the most important features is given below.

Do you want to check out the app for free? You can test the app and all its features without any limitations for two weeks. Simply install its free trial version from: https://play.google.com/store/apps/details?id=com.vcard.android.free

You would like to access the next major update bringing a novel user interface, new features, and guidance/support system?  Then check out the open beta test here:
https://play.google.com/apps/testing/com.vcard.android

The app has been successfully tested with more then 50 different CardDAV Servers like Nextcloud, Apple iCloud, Fruux, Marketcircle Daylight, Synology, or Owncloud. You can find a list of tested systems here: http://ntbab.dyndns.org/apache2-default/seite/carddavproviderCE.html

Overview on the most important features:
⊛Comprehensive support - Questions or suggestions? Simply write me a mail.
⊛Syncs with many different sources - CardDAV, WebDAV, FTP, HTTP, Cloudstorage, local files, mail attachments and many more (Of course, it also supports encryption and two way sync)
⊛Complex configuration? No worries, the app guides you through all the steps
⊛Create backups or archive your contacts manually or automatically 
⊛Flexibility - There are already contacts/groups stored on the device which should be pushed to the server? You need individual sync intervals for each of your contact data sources? No worries, this is possible!
⊛Designed for high speed and resilient address book synchronization
⊛Seamless integration with your device and your preferred contact apps
⊛Secure: All the sensitive information are encrypted before they are stored
⊛No secrets, you can - if you wish - always see what is happening and why
⊛Supports complex address books situations, servers and clients
⊛Supporting vCards (contacts/groups) in all available versions (4.0, 3.0, and 2.1)
⊛Supports self-signed certificates 
⊛Can create calendar entries for birthdays, anniversaries and other events
⊛Unique solutions for a variety of common and rare tasks. You have special requirements? Then the app is likely your solution. 
⊛New device? Switch from trial to full version? Simply export\backup your configuration and import it on the new device or the full version
⊛The app handles more contact/group data then other apps, an overview is given at http://ntbab.dyndns.org/apache2-default/seite/contactsync.html
⊛Multilingual: Supports English, German and partly French, Russian
If you are interested in translating the app then simply send me a mail.

Interesting features for large-scale orders:
⊛Setup and configure your server connections through adb
⊛Licensing for large-scale orders

Permissions:
You can find detailed information to the permissions at our website.

If you struggle with the configuration or need some assistance please contact me at consync@gmx.at. If you only add your questions to the comments I can hardly help you because I commonly need more information about your configuration and so on. I'm sure that I can help you to reach your goals and that I can provide the necessary support :)

Sync your contacts with CardDAV, FTP, HTTP, WebDAV servers or local files

ContactSync - CardDAV and more

Additional Information