https://marco.org/2008/10/30/tumblrs-lead-developer-marco-arment-is-also
Tumblr’s lead developer Marco Arment is also something of an entrepreneur on the side. His most useful creation is Instapaper, a simple bookmarking service hooked to an iPhone App which comes in free and pro versions.
— Silicon Alley Insider. Thanks! I guess you didn’t like Tumblr, then?