Dan Siroker turned his experience running analytics for Obama's 2008 campaign into Optimizely, a company built around the kind of testing tools he wished he'd had at the time, and losing his hearing in his twenties pushed him toward building products that help extend human memory and cognition. He's known for radical transparency as a founder, including publicly sharing his own investor pitch and 360 reviews, and for a disciplined approach to building products: trusting his own gut over outside consensus and always choosing quality and speed over scope.