Gregg 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 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


Gregg is an Invited Expert at the World Wide Web Corporation working in the CSV on the Web Working Group, Shape Expressions Community Group, Credentials Community Group, RDF Working Group, RDFa Working 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.


People I work with

This document describes Gregg, and is encoded with FOAF information encoded using HTML+RDFa 1.1. This information also available in alternate formats: RDF/XML Turtle. This document describes the same person as