The Invisiblehand API brings this cleverly named browser add-on focused on finding the lowest price for something that the user is shopping for to a wider audience. Constantly updating prices on millions of products from books to air fares, Invisiblehand stands out for its ability to learn about new products it hasn't seen before. The documentation indicates this is a RESTful API with JSON responses.
"APIs are first class-products at eBay," Gail Frederick, eBay Vice President of Developer Ecosystem, commented in a recent news story. In support of this statement, eBay this week announced numerous API enhancements and brand new APIs with the intent of empowering developers.