Stewart Butterfield

Current Company

Slack — Co-Founder

Two Pivots, Two Category-Defining Companies

Stewart Butterfield has one of the most unusual entrepreneurial records in Silicon Valley: he twice set out to build a video game and twice ended up creating a category-defining software product instead. The first pivot produced Flickr, the pioneering photo-sharing platform that was acquired by Yahoo in 2005 for an estimated $35 million. The second produced Slack, the workplace messaging tool that redefined how teams communicate and was acquired by Salesforce in 2021 for $27.7 billion.

Born in a remote fishing village in British Columbia, Stewart Butterfield studied philosophy at the University of Victoria and Cambridge before turning to technology. His academic background in philosophy and cognitive science gave him a product sensibility that prioritized user experience and delight — qualities that became Slack's signature. Butterfield understood that enterprise software didn't have to feel like enterprise software, and that insight turned Slack from an internal tool into a phenomenon.

Making Work Less Painful

Stewart Butterfield launched Slack in 2013 as a better alternative to email for team communication. The product grew from zero to over 12 million daily active users in just a few years, with companies adopting it bottom-up as employees brought it into their organizations before IT departments formally approved it. That viral, consumer-style growth pattern in an enterprise product was nearly unprecedented at the time.

As CEO of Slack, Stewart Butterfield built a culture that valued craft, humor, and empathy — reflected in everything from the product's playful loading messages to its inclusive design principles. After the Salesforce acquisition, Butterfield stepped down as CEO in 2023, leaving behind a company that had fundamentally changed the way knowledge workers collaborate and had proven that there was a massive market for making work communication less painful.