Gregg has been a software executive and entrepreneur since 1997. He started three companies in Marin County. He consults on linked-data projects and volunteers as an Invited Expert for the World Wide Web Concortium (W3C).

Gregg is a primary force behind all three formats used for encoding schema.org formats:

  • Microdata (as editor of the Microdata to RDF specification),
  • JSON-LD (as one of three editors of the JSON-LD specifications), and
  • RDFa (as a primary contributor to RDFa 1.1 specifications).


Gregg has been a software executive and entrepreneur since 1997. He started three companies in Marin County, including Cafex Corporation, Xippix Inc., and Siterra Corporation. Gregg’s skills as an engineering manager and software architect helped propel these companies to success in the fast moving Internet environment.

Prior to starting Cafex, in 1997, Gregg was a systems architect and software manager in several notable Silicon Valley ventures, including:

There he specialized in designing cutting edge operating systems development, including

Gregg Kellogg’s Resume

Past Projects

  • Connected Media Experience: media enrichment projects using open stack protocols, RDF and HTML5.
  • Gracenote: Media systems architecture and prototyping (Ruby on Rails and Adobe Flex).
  • Macy’s West Advertising: General IT consulting including specification of design processes to be used for internal projects.
  • ChaCha Search: Designed and developed the ChaCha Underground using Ruby on Rails and MySql.


Gregg is an Invited Expert at the World Wide Web Consortium working in the CSV on the Web Working Group, RDF Working Group, RDFa Working Group, Credentials Community Group, and Linked JSON Community Group. Gregg is also the editor of the Microdata to RDF Note.

Gregg is avidly interested in The Semantic Web, Linked Data, and Ruby.

Open Source projects

Ruby RDF
A number of Ruby gems implementing elements of the Resource Description Framework (RDF) including parsers and serializers for RDFa 1.1, HTML Microdata, RDF/XML, Notation-3 and Turtle. Complete SPARQL 1.0 parser and runtime engine written in pure Ruby.


This information also available in alternate formats: RDF/XML Turtle. This document describes the same person as http://foaf.me/gkellogg#me.

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