Yahoo is allowing external developers to build applications that use Yahoo members' lists of contacts, after opening up the application programming interface (API) to its Address Book service.
The Address Book API is Yahoo's second major step in its long-range and ambitious Open Strategy (Y OS) initiative to open all Yahoo sites, online services and web applications to outside developers, and give users a 'social profile' dashboard to unify and manage their Yahoo services.
Last month, Yahoo made available to all developers its Search Monkey platform for creating applications to enhance its web search results and, in theory, make them more appealing and useful.
"This Address Book API is the second major proof point for Y OS," said Chris Yeh, head of the Yahoo Developer Network. "We're taking one of the richest sources of information at Yahoo and opening it up so third-party developers can access that data."
There has been much demand among external developers for the Address Book API, which Yahoo had made available to hand-picked partners like Plaxo and LinkedIn, but not broadly to everyone, until Wednesday.
With the new API, Yahoo expects to make it unnecessary for developers to scrape contact-list data from Yahoo members' address books, Yeh said. That practice is inefficient from a programming standpoint, as well as insecure, because it often requires that Yahoo members provide external sites with their log-in information to Yahoo services, he said.
"Now we have a specific authentication protocol [for address book data]," Yeh said.
Applications that employ this API will not require that Yahoo members provide their log-in data, because the authentication happens on Yahoo's system.
In addition, the API provides for synchronising changes made to Address Book data with its external applications so that the information is always current, as opposed to the one-time data transfer of scraping, he said.
The Address Book service works with Yahoo Mail, Yahoo Messenger and Yahoo Go, but it's not the only service where Yahoo users can store lists of contacts. For example, the contact lists in the Yahoo 360 social network and the photo-sharing site Flickr aren't integrated with the Address Book.
Eventually, as part of Y OS, Yahoo will unify into a single, centralised Address Book repository all the contacts lists in its different sites and services, Yeh said.
Uses for the API could include functions for sending out 'friend' invitations in social networks, obtaining physical addresses for shipping purposes and getting phone numbers for mobile applications.
Built into the API is search functionality, so that applications can look for specific contacts. Yahoo is using its own Browser Based Authentication (BBAuth) technology for the API, but plans to later support the OAuth standard.