Jason Grigsby is co-founder of Cloud Four, a small web agency in Portland, Oregon. He co-authored Head First Mobile Web for O'Reilly, was part of the team that worked on the Obama '08 iPhone app, founded Mobile Portland along with the first open device lab; and was a signatory to the Future Friendly Web manifesto. Jason was bit by the mobile bug in 2000 when WAP was crap. He participated in the Responsive Images Community group and has written numerous articles on how to use responsive images. He is currently obsessed with the potential of Progressive Web Apps.