WeChat is a social media with instant messaging, commerce and payment services application.

Baïkal is a Cal and CardDAV server, based on sabre/dav, that includes an administrative interface for easy management.

Soocial provides a synchronization service that syncs contacts between the users' computers, phones and web apps.

FullContact gives you all the power of your address book, right in your Gmail inbox.

fruux is a cross-platform synchronization service.

AkrutoSync helps you automatically sync Outlook across all devices.