Cal Henderson is the co-founder and CTO of Slack. He oversees Slack's world-class engineering team and sets the technical vision for the company. He is an experienced technology leader, having previously built and led the engineering team at Flickr from its founding through its acquisition by Yahoo. He is a popular speaker on engineering scalability and authored the best-selling O’Reilly Media book “Building Scalable Websites”. In 2019, he was named a Fortune 40 Under 40 honoree and recognized by the World Economic Forum as a Young Global Leader.