News 

The move could see the creation of syncing tools that work seamlessly with Google account services such as GMail.

User's contact books are currently shared between the GMail, Calendar, and Reader services, but the release of an API will open the data up for a variety of uses.

The API allows external websites and applications to read, create, update and delete contacts, which are stored in the Google Data Format, based on Atom.

"We know that this Google Data API is the most requested feed by our developer community, so we're very excited about this release," says Sebastian Kanthak of the Google Contacts team in a blog post.

"We hope that APIs like this one mean you will never have to give out your username and password to other sites again."