In 2006, Harrington co-founded Picnik with friend and former colleague Darrin Massena, which was later acquired by Google in March 2010. Harrington left Google in March 2011, and co-founded another company with Massena, called Catnip Labs, in January 2012. Harrington was the CTO at The Committee for Children from 2016-2018 and is now the CTO of Amplion.