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WhatsApp Co-Founder to Lead Signal Messaging App as Interim CEO

WhatsApp co-founder Brian Acton most notably joined the #DeleteFacebook movement back in 2018.

 & Michael Kan Principal Reporter

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Messaging app Signal is getting a new interim CEO in Brian Acton, the WhatsApp co-founder who left Facebook on bad terms several years ago.

Outgoing Signal CEO Moxie Marlinspike announced today that he's stepping down after spending almost a decade developing the code behind the encrypted messaging service. 

“It has always been my goal for Signal to grow and sustain beyond my involvement,” Marlinspike wrote in a blog post. Four years ago, he was in charge of writing most of the code for the Signal messaging service. Since then, the development team has expanded to 30 people. 

“​​Simultaneously, Signal has grown in adoption and popularity around the world even faster than I imagined,” he added. “It’s difficult to overstate how important Signal is to me, but I now feel very comfortable replacing myself as CEO based on the team we have, and also believe that it is an important step for expanding on Signal’s success.”

Marlinspike will remain a board member for the Signal Technology Foundation, which helps run the app. He’s also been interviewing candidates to replace him. But in the meantime, he’s tapping Acton to lead as interim CEO. 

Brian Acton
Brian Acton

“I have every confidence in his commitment to the mission and ability to facilitate the team for this time,” Marlinspike said. 

Acton is perhaps best known for founding WhatsApp with computer programmer Jan Koum. The duo sold their messaging app to Facebook in 2014 for $16 billion. However, Acton eventually left the social network in 2017 on bad terms over Facebook’s plan to monetize WhatsApp.

He then joined with Marlinspike to found Signal, an end-to-end encrypted app that competes with WhatsApp for users. In 2018, Acton also voiced his opposition to Facebook by tweeting out: “It is time. #deletefacebook,” amid the Cambridge Analytica scandal. Like Marlinspike, Acton also currently serves as a board member on the Signal Technology Foundation.

About Our Expert

Michael Kan

Michael Kan

Principal Reporter

My Experience

I've been a journalist for over 15 years. I got my start as a schools and cities reporter in Kansas City and joined PCMag in 2017, where I cover satellite internet services, cybersecurity, PC hardware, and more. I'm currently based in San Francisco, but previously spent over five years in China, covering the country's technology sector.

Since 2020, I've covered the launch and explosive growth of SpaceX's Starlink satellite internet service, writing 600+ stories on availability and feature launches, but also the regulatory battles over the expansion of satellite constellations, fights with rival providers like AST SpaceMobile and Amazon, and the effort to expand into satellite-based mobile service. I've combed through FCC filings for the latest news and driven to remote corners of California to test Starlink's cellular service.

I also cover cyber threats, from ransomware gangs to the emergence of AI-based malware. In 2024 and 2025, the FTC forced Avast to pay consumers $16.5 million for secretly harvesting and selling their personal information to third-party clients, as revealed in my joint investigation with Motherboard.

I also cover the PC graphics card market. Pandemic-era shortages led me to camp out in front of a Best Buy to get an RTX 3000. I'm now following how the AI-driven memory shortage is impacting the entire consumer electronics market. I'm always eager to learn more, so please jump in the comments with feedback and send me tips.

The Best Tech I've Had:

  • My first video game console: a Nintendo Famicom
  • I loved my Sega Saturn despite PlayStation's popularity.
  • The iPod Video I received as a gift in college
  • Xbox 360 FTW
  • The Galaxy Nexus was the first smartphone I was proud to own.
  • The PC desktop I built in 2013, which still works to this day.

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