Stewart Butterfield Net Worth

Stewart Butterfield has an estimated net worth of $1.6 billion, according to Forbes Real-Time Billionaires, Stewart Butterfield profile (figures as of October 20, 2026). That is down from a peak of $1.7 billion.

Stewart Butterfield is a Canadian tech entrepreneur best known for cofounding Flickr and Slack. He started in web design and worked on Gradfinder.com in 2000 before launching Ludicorp in 2002 with Caterina Fake and Jason Classon. Ludicorp first worked on Game Neverending, then shifted into Flickr. Yahoo bought Flickr in 2005 for $35 million, and Butterfield stayed on as Flickr’s general manager until 2008.

His biggest business win came with Slack, the team communication tool built at Tiny Speck while the company was working on Glitch. Slack was announced in 2013 and released publicly in 2014, growing quickly with strong user adoption. By 2015, Slack had raised US$340 million and passed 2 million daily active users. In 2021, Salesforce acquired Slack for $27.7 billion in cash and stock, a deal that became the main source of Butterfield’s fortune.

How Stewart Butterfield built his wealth

Butterfield’s wealth comes from messaging software and earlier internet startups. After working on Gradfinder.com and freelance web design, he helped start Ludicorp in 2002. That company moved from an online game to Flickr, a photo-sharing site that Yahoo bought in 2005 for $35 million. He later cofounded Tiny Speck in 2009, and the work on its game Glitch led to Slack, which became the company’s breakout product.

Slack turned Butterfield into one of the best-known founders in business software. The product was released publicly in 2014 and expanded fast, with more than 120,000 daily users registered in the first week of August and nearly 16,000 users registered without any advertising. In 2019, Slack announced its initial public offering with an opening price of $38.50 and a market capitalization of US$21.4 billion. Salesforce then bought the company in 2021.

What Forbes says about his fortune

Forbes placed Butterfield at $1.7 billion in 2021, then $1.4 billion in 2022 and $1.3 billion in 2023. The estimate rose back to $1.7 billion in 2024 before edging down to $1.6 billion in 2025. Forbes currently puts his net worth at $1.6 billion on its real-time billionaires tracker as of October 20, 2026. Across Forbes, his wealth is tied to technology and messaging software.

The biggest money event in his career was Slack’s $27.7 billion sale to Salesforce in 2021. That transaction followed years of growth after Slack came out of Tiny Speck’s work on Glitch. Butterfield departed Salesforce in 2022, after the acquisition had already made Slack the central reason for his billionaire status. Earlier in his career, Flickr’s 2005 sale to Yahoo gave him a successful exit long before Slack became his defining company.