Per provider, this API will be shutting down on March 31, 2016
BOSS (Build your Own Search Service) is Yahoo!'s open search web services platform. The goal of BOSS is simple: open up Yahoo!'s search infrastructure and enable third parties to build revolutionary search products leveraging their own data, content, technology, social graph, or other assets. Developers, start-ups, and large Internet companies can use BOSS to build and launch web-scale search products that utilize the entire Yahoo! Search index. BOSS gives you access to Yahoo!'s investments in crawling and indexing, ranking and relevancy algorithms, and powerful infrastructure. By combining your assets and ideas with our search technology assets, BOSS is a platform for the next generation of search innovation. The API uses a RESTful interface and responses are formatted in XML and JSON.