Cal Henderson is Co-Founder and CTO at Slack Technologies, a cloud-based collaboration platform that was acquired by Salesforce for $27.7 billion in 2021. He oversees Slack's world-class engineering, research and design teams and sets the technical vision for the company.

Cal graduated with a degree in software engineering from Birmingham City University in 2002 and built and led the engineering team at Flickr through its acquisition by Yahoo. He is a pioneer in web APIs and created the basis for OAuth and oEmbed, now used by YouTube, Twitter, and many others.

Cal authored the bestselling O'Reilly book Building Scalable Websites and was named a Fortune 40 Under 40 honoree in 2019. He was recognized by the World Economic Forum as a Young Global Leader and now serves as a Venture Partner at Odyssey Ventures.

Slack grew from an internal tool at gaming company Tiny Speck into one of the fastest-growing SaaS companies in history, raising over $1.2 billion in funding. The company went public on the NYSE in 2019 via direct listing before its acquisition by Salesforce.

Under Cal's technical leadership, Slack grew to serve millions of daily active users across Fortune 500 companies and beyond. The platform has transformed workplace communication and collaboration, with customers ranging from SpaceX and Nike to corner stores and dairy farms.