I am trying to programatically perform a search on Microsoft Bing search engine. Here is my understanding: There was a Bing Search API 2.0 , which will be replaced soon (1st Aug 2012) The new API is known as Windows Azure Marketplace. You use different URL for the two. In the old API (Bing Search API 2.0), you specify a key (Application ID) in the URL, and such key will be used to authenticate the