Geraint was born in Stockport and attended William Hulme's Grammar School in Manchester, before winning a scholarship to study classics at Pembroke College, Oxford. At Oxford, he rowed for both Pembroke and Oxford, and was captain of the Oxford Lightweights.

After graduating, Geraint worked for Logica in London, and co-authored a book on UNIX programming. In 1988, he joined Microsoft, spending several years in Seattle and Paris, and then working at the UK Development Lab in Hampshire, where he was architect and lead developer of DirectShow.

In 1996, Geraint moved to Anglesey, and spent the next 18 years working as a freelance consultant on digital video. In 2014, Geraint was hired to write the video streaming framework for Periscope, and joined the company fulltime in January 2015.

Geraint is married and has three daughters. He and Judy live in Anglesey with their spaniel, Jack.