WhatsApp co-founder and Facebook board member Jan Koum is leaving the company after leaked reports of clashes over Facebook's plans to use WhatsApp users' personal data and weaken its encryption.

Referring to his former partner Brian Acton, Koum wrote on his Facebook page:  "It's been almost a decade since Brian and I started WhatsApp, and it's been an amazing journey with some of the best people."  Acton left the company last November.  Koum continued, "But it is time for me to move on."  His status included a Facebook "emotional" tag indicating that he is "sad."  He did not elaborate on the differences over Facebook's privacy issues.

Facebook bought WhatsApp in 2014, and divisions over Facebook's policies about collecting the personal data of its users popped up early in the combined company's brief history.  But it came to a head this year, as Koum even supported the "#DeleteFacebook" movement.  He has also indirectly made the point by contributing $50 Million to the Signal Foundation, which develops and supports the encrypted-messaging app Signal (arguably WhatsApp's largest competition as of late).

Facebook is planning some changes to WhatsApp.  Users will soon have access to features such as stickers and group video calls.  And Facebook vice president of messaging products David Marcus said that users will see more ads.

"As far as advertising is concerned, we're definitely getting WhatsApp more open," Marcus said.  "We're now going to have the ability to enable larger companies, not only small businesses, to integrate a new API (application programming interface) to send and receive messages with people on the Whatsapp platform," he added.