Where Does Work Happen at Slack? A Look Into the Popular Communication Tool’s Org Chart

Bessie LiuOrg Charts
Stewart Allen Cal NYSE

Slack's leadership team outside the New York Stock Exchange after the company went public in 2019. Image courtesy of Slack.

Slack is known as one of the fastest-growing startups, reaching $1B in valuation in just nine months of launching -- and without spending any money on traditional marketing.

Now, the company is being acquired by Salesforce in a megadeal worth $27.7B. The Org has taken a look into the executive team of the startup unicorn that has changed workplace communication.


Prior to founding Slack, CEO Stewart Butterfield was already well known in the startup space as the co-founder of the popular photo-sharing app Flickr. He began working on Slack in early 2013, but the company didn’t start out to be a workplace communication tool. Initially, Butterfield and his team had intended to build a web-based multiplayer game called Tiny Speck, but during the game’s development the team saw the potential to scale the internal communication tool that they were using.

“We have developed some unique messaging technology with applications outside of the gaming world and a smaller core team will be working to develop new products,” an announcement by Tiny Speck read.

Unlike traditional businesspeople, Butterfield has a rather unique educational background. The Canadian entrepreneur is a graduate of Cambridge and the University of Victoria, where he majored in philosophy. He started his career at IT consultancy company then worked as a Software and Internet Product Design Consultant for six years before founding Flickr. Among his many titles, Butterfield has been recognized as one of the 100 most influential people in the world by Time Magazine and Technology Innovator of the Year by Wall Street Journal.

Stewart Butterfield

Slack CEO, Stewart Butterfield. Image courtesy of Slack.

Cal Henderson is Butterfield’s technical co-founder who currently serves as the company’s CTO. Henderson previously led Flickr’s engineering team after it was acquired by Yahoo. The software engineering graduate from the University of Central England has previously served as the Director of Technology for content, subscription, and networking business, EMAP. He has also worked as the Director of Web Development for LudiCorp Research and Development. He has previously been named 40 under 40 by Fortune magazine.

Cal Henderson

Slack CTO, Cal Henderson. Image courtesy of Slack.

Perhaps the reason why Slack has grown in popularity is that it has been designed to be addictive, combining clever interactive user interfaces with simple messaging, something its competitors have not been able to achieve. As Slack continues to innovate, the Chief Product Officer, Tamar Yehoshua, plays an essential role in ensuring that the product remains relevant and seamless to use.

A graduate of the University of Pennsylvania, Yehoshua has previously served as VP of Advertising Technology at a former Amazon subsidiary -- A9. She later left to join Google, where she was the VP of Product and Engineering. She currently sits on the board of Yext, an AI Search Company.


Slack CPO, Tamar Yehoshua. Image courtesy of Slack.

Overseeing the company’s finances is CFO Allen Shim. Another graduate from the University of Pennsylvania, Shim started his career as a Research Associate at Citi. He later joined research and brokerage firm AB Bernstein before joining Yahoo’s business operations team. Before joining Slack in 2014, Shim was the VP of Finance and Treasurer of YuMe, a marketing and advertising firm.

Allen Shim

Slack CFO, Allen Shim. Image courtesy of Slack.

As data privacy becomes a more significant concern, Slack onboarded its first CSO Sean Catlett in 2020. Catlett, an industry veteran, has previously served as Reddit’s CISO and was the CEO of Pharos Security, a computer and network security company headquartered in Toronto. The University of Texas graduate has also worked as SVP at the Bank of America and was the Global Head of Threat and Vulnerability Management at Barclays.

“With the global shift to remote work, the threat landscape is evolving faster than ever before,” Henderson said in a press release. “Our customers have complex and rigorous security needs, particularly those in the financial services, health care and government sectors. Sean’s leadership experience at financial services, consumer and enterprise companies, as well as his deep technical expertise, will make him an invaluable partner to our executive team and our customers.”


Slack CSO, Sean Catlett. Image courtesy of Slack.

As Slack prepares for the post-pandemic world, the company is confident that remote work will not come to a halt and will continue to design its product to cater to the changing landscape of physical and virtual offices.


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