Alexa began a partnership with Google in early 2002, and with the web directory DMOZ in January 2003. In December 2005, Alexa opened its extensive search index and Web-crawling facilities to third-party programs through a comprehensive set of Web services and APIs. These could be used, for instance, to construct vertical search engines that could run on Alexa's servers or elsewhere. In May 2006, Google was replaced with Windows Live Search as a provider of search results. In December 2006, Amazon released Alexa Image Search. Built in-house, it was the first major application built on the company's Web platform. In May 2007, Alexa changed their API to limit comparisons to three websites, reduce the size of embedded graphs in Flash, and add mandatory embedded BritePic advertisements.