One successful company is hard enough. These Bay Area serial founders have done it multiple times, each time starting over, often from scratch, and often in a completely different direction from what made them famous.
Stewart Butterfield: Flickr to Slack
Stewart Butterfield was born Dharma Jeremy Butterfield in 1973 in a log cabin in Lund, British Columbia, without running water or electricity. His family lived on a commune until he was five. He studied philosophy at the University of Victoria and earned a master’s degree in philosophy from Clare College, Cambridge, before moving to San Francisco and building two of the most influential consumer technology products of the past two decades.
The first was Flickr. In 2002, Butterfield co-founded Ludicorp with his then-wife Caterina Fake and Jason Classon to build an online multiplayer game called Game Neverending. The game failed to attract an audience. A photo-sharing feature built inside it did not. They spun it off as Flickr in 2004. Yahoo acquired Ludicorp and Flickr in March 2005, and Butterfield stayed on as General Manager of Flickr until leaving Yahoo in 2008.
He tried again in 2009, co-founding Tiny Speck with many of the same colleagues to build another online game, this one called Glitch. It launched in 2011 and shut down in December 2012. The internal communication tool the Tiny Speck team had built to coordinate their work during development turned out to be more useful than the game itself. In August 2013, Butterfield announced the release of Slack. It reached a $1 billion valuation eight months after public launch in February 2014, making it the fastest company to reach unicorn status at the time. It went public in June 2019 and was acquired by Salesforce for $27.7 billion in 2021. Butterfield left as CEO in December 2022. Both of his billion-dollar companies were accidents. Both began as failed games.
Evan Williams: Blogger to Twitter to Medium to Mozi
Evan Williams grew up on a farm in Clarks, Nebraska, attended the University of Nebraska for about a year and a half, and left without graduating. He made his way to California, spent time at several Bay Area tech companies, and in 1999 co-founded Pyra Labs with Meg Hourihan to build project management software. A note-taking feature built inside the project management tool became Blogger, one of the earliest platforms for publishing personal content on the web. Williams coined the term blogger and was instrumental in popularising the word blog. Google acquired Pyra Labs and Blogger in February 2003. Williams left Google in October 2004.
His next company was Odeo, a podcasting platform, which he co-founded in 2004. When Apple added native podcast support to iTunes, Odeo’s core thesis became untenable. A side project being built inside the company by Jack Dorsey became Twitter. Williams co-founded Twitter in 2006, served as its CEO from 2008 to 2010, and remained on its board until 2019. In 2012 he launched Medium, an online publishing platform designed to elevate the quality of writing on the internet. In 2014 he co-founded Obvious Ventures, a venture capital firm focused on companies he describes as world-positive.
His latest venture is Mozi, which he co-founded in 2024 with entrepreneur Molly DeWolf Swenson. Mozi is a private social network with no public profiles and no follower counts, designed to facilitate in-person meet-ups by alerting users when contacts are in the same city or attending nearby events. It has raised $6 million from investors including Obvious Ventures. The direction is a deliberate retreat from the dynamics Williams spent 25 years building. Bloomberg described it as Williams going in a different direction entirely.
Kevin Systrom: Instagram to Artifact
Kevin Systrom graduated from Stanford in 2006 with a degree in management science and engineering, spent two years at Google working on Gmail, Google Calendar, and Google Docs, and left out of frustration at not being elevated into the product management track. He co-founded Instagram in 2010 with Mike Krieger, starting from a location check-in app called Burbn before stripping it back radically to focus on photos, filters, and sharing. Instagram reached one million users within two months of launching and 10 million within a year. Facebook acquired it for $1 billion in 2012 with just 13 employees. By the time Systrom resigned as CEO in September 2018 amid reported tensions with Mark Zuckerberg over creative control, Instagram had 800 million monthly users. It now has more than 3 billion, generating over $20 billion annually for Meta. Systrom has not posted on the platform he built since May 21, 2018.
In January 2023, Systrom and Krieger returned with Artifact, an AI-powered news aggregation app that used machine learning to personalise a reading feed. It quickly attracted a loyal following and was described variously as TikTok for text and a smarter alternative to algorithmically chaotic social feeds. In January 2024, Systrom announced the app would shut down, concluding that the market opportunity was not large enough to justify continued standalone investment. Yahoo acquired Artifact in April 2024, integrating its personalisation technology into Yahoo News. Systrom joined as a strategic advisor during the transition. He currently serves on the board of Walmart.
Brian Acton: WhatsApp to Signal
Brian Acton grew up in Michigan, attended Stanford on a scholarship, and graduated in 1994 with a degree in computer science. He spent nearly a decade at Yahoo, where he met Jan Koum. The two left together in 2007, traveled South America for a year, applied to Facebook and were rejected, and co-founded WhatsApp in 2009 as a simple, ad-free, encrypted messaging platform. Facebook acquired WhatsApp in February 2014 for $19 billion. Acton’s stake was worth approximately $3 billion at the time of the deal.
He stayed at Facebook for three years and left in September 2017, walking away from approximately $850 million in unvested stock options over disputes with Facebook leadership regarding the monetization of WhatsApp and the use of user data for targeted advertising. In February 2018, he co-founded the Signal Foundation with cryptographer Moxie Marlinspike, seeding it with a $50 million interest-free loan due for repayment in 2068, and then extended to $105 million by the end of that year. Signal is an open-source, encrypted messaging platform with no revenue model, funded entirely by donations.
When Marlinspike stepped down as CEO in January 2022, Acton served as interim CEO during the search for a replacement. In June 2023, Signal confirmed Acton would remain as CEO. As of January 2025, Signal had approximately 70 million monthly active users and had been downloaded more than 220 million times. John Ratcliffe, in his role as CIA director, confirmed in 2025 that Signal is installed by default on the devices of most CIA employees. In March 2025, it emerged that senior members of the Trump administration had been using Signal to discuss sensitive military information, inadvertently adding The Atlantic’s editor-in-chief to the group chat.
Reid Hoffman: SocialNet to LinkedIn to Inflection AI to Manas AI
Reid Hoffman was born in Palo Alto, earned a degree in symbolic systems from Stanford and a master’s degree in philosophy from Oxford as a Marshall Scholar, and worked at Apple on eWorld, an early online service, before leaving in 1996. In 1997 he founded SocialNet, one of the earliest online social networking platforms, designed to connect people through shared interests and relationships. It did not achieve meaningful adoption. In 2000 he joined PayPal as COO, became part of the founding network later known as the PayPal Mafia, and in December 2002 co-founded LinkedIn, which launched in May 2003.
LinkedIn became the world’s largest professional networking platform, went public in 2011, and was acquired by Microsoft in 2016 for $26.2 billion. Hoffman joined Microsoft’s board of directors. In 2022 he co-founded Inflection AI, a conversational AI company that raised $1.3 billion before its founding team, including CEO Mustafa Suleyman, was effectively hired by Microsoft in a controversial arrangement in 2024 that drew scrutiny from the UK Competition and Markets Authority and the US Federal Trade Commission.
In January 2025, Hoffman co-founded Manas AI with Siddhartha Mukherjee, a Pulitzer Prize-winning oncologist and author of The Emperor of All Maladies. Manas AI is an AI-driven drug discovery company focused on accelerating the development of cancer treatments, raising approximately $24.6 million in initial funding. It is Hoffman’s fourth company. He is 57.
