Brian Acton, the co-founder of WhatsApp, is leaving the popular Facebook-owned company to launch his own nonprofit foundation.

Acton, who launched WhatsApp with CEO Jan Koum eight years ago, announced his departure in a Facebook post on Tuesday (12 September). He wrote: "I have decided to move on and start a new chapter in my life" – a "non-profit focused at the intersection of nonprofit, technology and communications."

"It's something I've thought about for a while, and now it's time to just focus and execute," the 45-year-old added. "I'll have more to share in the coming months." He will officially leave the company in November, according to VentureBeat's sources familiar with the matter.

Acton, a Stanford alumnus and a former Apple employee, worked with Ukrainian immigrant Koum at Yahoo. The duo left the company in 2007 to start WhatsApp in 2009.

The internet messaging service has grown into one of the biggest platforms in the world with 1.3 billion users and over a billion daily active users. It is not active in some countries but has grown exponentially in Brazil, Mexico, Russia and India.

"This decision is, of course, a tough one. I'm proud of what our team has accomplished in only a few years, and it's humbling to see that so many people rely on WhatsApp every day," Acton said in his post.

WhatsApp was acquired by Facebook in 2014 for $19bn in a cash and stock deal. The social media giant has not yet commented on Acton's departure.