Portable Contacts was an open protocol for developers to make it easier for developers to give their users a secure way to access the address books and friends lists they have built up all over the web. The goal of the project was to increase data portability by creating a common and open specification to bridge proprietary contacts Application programming interfaces (API) such as Google's GData Contacts API, Yahoo's Address Book API, and Microsoft's Live Contacts API. It combines OAuth, XRDS-Simple and a wire-format based on vCard harmonized with schema from OpenSocial.
- "Developer's Guide - Portable Contacts API - Google Code". Google Inc. Retrieved 2011-07-18.
- Logan, Angus (2010-06-28). "Developing with Messenger Connect: Recognizable & intuitive". Retrieved 2011-07-18.