Introducing the all new Yahoo! Contacts API

We are pleased to announce the launch of the new Yahoo! Contacts API, which now uses OAuth to offer read, write, and sync access to the Yahoo! Address Book, one of the largest address books on the Web. We've completely reengineered the existing Contacts API and added more useful functionality for developers.

The new Contacts API provides the same features as the Yahoo! Address Book API, plus it is part of the Social API stack. Hence, it is fully compliant with the rest of the social APIs provided by Yahoo! such as Social Directory, Updates and the Status API. This allows you to mash up the APIs to create social applications for users on and off Yahoo!. To get started, visit the Contacts API documentation.

With this release, we are also going to stop active development on the old Address Book API. If you are currently using the BBAuth-based Address Book API, we encourage you to migrate to the new API so you can take advantage of the following new features, with many more to follow shortly!

  • Update contacts automatically: When two users create a “connection,” the contact info in their address books is automatically kept in sync from that point on. So, if a user really cares about a friend and creates a “connection” with that friend, the user will see his address book update automatically when the friend changes contact information in their social profile.
  • Get data faster and more reliably: More than half a billion unique visitors come to Yahoo! monthly, so reliability and scalability are of cardinal importance. Thus, Yahoo! has made sure that the new API is faster and more reliable, so you don't have to worry about business continuity issues.
  • Identify the users' trusted contacts: A user's address book often contains contacts who have a wide range of relationships with the user. The Contacts API allows you to sort the user's most socially relevant contacts (aka connections). For example, a user may have the email address of his or her dentist in their address book, but that contact is probably not as socially relevant to the user as a friend or family member.
  • Filter contacts more efficiently: We've also added a number of filter mechanisms that allow you to fetch a subset of contacts by specifying matrix parameters.

We are very excited about this launch and look forward to seeing how you use the new Contacts API to create innovative and engaging applications.

UPDATE (September 2010): Here's a sample implementation of Hybrid OAuth. OAuth is the recommended way to access Yahoo! APIs. We do not permit asking users for their username and password outside of a Y!-hosted login page, as it's an unsecure way of accessing users data.

You may also find some helpful docs on the .NET SDK for OAuth and Contacts API forum and the .NET Developer Center.