Yahoo Inc. plans to introduce today the Yahoo Search Developer Network (YSDN), an online resource offering developers access to new Web services application programming interfaces (APIs) for Yahoo Search products, along with Overture's existing APIs. Yahoo envisions YSDN as a place where developers can share code, ideas, and applications that extend the company's search technology.

"We've been asked by a lot of third-party developers for these APIs for a while," says Eckert Walther, head of product management for Yahoo Search. "And we've recognized that search has gone from a consumer application to a much broader application platform."

As an example of how the APIs might be used, Walther suggests that a Web site about restaurants in Palo Alto might want to show those restaurants on a map. "You could show that directly with the Yahoo Local search API," he explains. "Or let's say you had a restaurant review site where people could provide quick reviews, and you wanted to supply a spell checker. You could do that using the spell checker API."

Platforms of course require the support of developers, which explains Yahoo's interest in supporting them. "This really helps us get more in touch with the developer community and the open source community," Walther says. "We've worked a lot on that lately. We've really been recognizing how much we want to work with those folks. So providing those APIs is good relationship building."

Other companies interested in search technology have been thinking along similar lines. A month ago, Google began offering an API for its AdWords program, similar to what Yahoo's Overture subsidiary has offered since 2001. To date, Microsoft has no search engine API, but according to Kevin Lee, executive chairman of search engine marketing firm Did-It.com, that's because MSN Search doesn't auction keywords the way Google and Yahoo do.

"That said, there's a consensus within the industry that Microsoft is working on something," he says, "and everyone expects that given how important APIs have become to the industry, they'd be crazy not to release an API. These keyword marketplaces can get very dynamic and you need a level of automation in order to get the most value. Automation actually encourages marketers to be a little freer with their budgets."

What Yahoo is offering, Walther contends, is much broader than what's offered by the competition. In a literal sense, that's true: Each API provides developers with access to 5,000 queries per day per API, five times more than the limits placed on users of the Google Web API. "We don't just have a Web search API," he explains. "We have Web, local, news video, image, and spelling, among others." And, he says, YSDN is about more than APIs; it's about the development community.

What Yahoo and its competitors hope the developer community can provide is new services that appeal to searchers. "If you have the searcher," says Lee, "the marketing dollars will come."