Stewart Butterfield
Co-founder of Flickr (2004, acquired by Yahoo) and Slack (2013, IPO 2019, acquired by Salesforce for $27.7B in 2021). Led Slack from launch to over 10 million daily active users. Known for articulating the comprehension-versus-friction distinction, the utility curve frame for product strategy, hyper-realistic work-like activities, and the ‘We Don’t Sell Saddles Here’ memo. Pivoted both Flickr and Slack from failed video game projects.