Morningstar then worked at "State Software", where he helped create the JSON format with Crockford in 2001. From 2003 to 2005, the worked at "Avistar Communications" as principal architect for a videoconferencing system. In 2005, he took joined Yahoo!, where he was the principal architect and development team leader for the Yahoo! Core Identity Platform (CoreID). CoreID is a system that provides a framework for the storage and retrieval for all users of Yahoo!. He was also a team leader of the Yahoo! Reputation Platform, as well as a member of Yahoo!'s Social Media advisory program.