SAN FRANCISCO — Jan Koum, who sold the messaging app WhatsApp to Facebook for $19 billion and became a board member of the social network, said he was leaving the company.
The announcement followed disagreements between Mr. Koum and Facebook’s leaders over the use of people’s data and the social network’s attempts to weaken encryption, according to a company executive with knowledge of the matter.
In a Facebook post on Monday, Mr. Koum said “it is time for me to move on.” He did not give a reason for his exit.
But according to the company executive, who asked not to be identified because the details of Mr. Koum’s departure were confidential, Mr. Koum had grown increasingly concerned over Facebook’s position on user data in recent years.
Mr. Koum, who co-founded WhatsApp and had insisted that strong encryption be built into the service, was perturbed by the amount of data that Facebook collected on people and had advocated for stronger protections of that information, according to the person. Mr. Koum had discussed leaving the company since late last year, the person added.
Facebook declined to comment beyond Mr. Koum’s post. Mr. Koum’s decision was earlier reported by The Washington Post.
Mr. Koum’s exit is the highest-profile departure from Facebook after months of controversy at the social network. The company has been under scrutiny for how Russian agents used it to influence voters before the 2016 presidential election and more recently for its lack of data protections for users, a subject that gained attention after revelations that the British political consulting firm Cambridge Analytica had improperly harvested the information of as many as 87 million Facebook users.
The controversies have set off disagreements among top Facebook executives about how to deal with those issues. In March, The New York Times reported that Alex Stamos, Facebook’s chief information security officer, intended to leave the company after an internal dispute over how to handle the threat of Russian influence efforts. Facebook has also reshuffled its top ranks in its Washington office, where lobbying and policy matters are handled.
Facebook’s business depends on getting people to spend time on its sites and allowing advertisers to target users based on their interests. WhatsApp has had no advertising on its service, but in recent years it has been sharing more information about its users with Facebook, its parent company.
In March, Brian Acton, who co-founded WhatsApp with Mr. Koum and who has since left the company, wrote on Twitter that it was time to delete Facebook after the Cambridge Analytica revelations.
Mark Zuckerberg, Facebook’s chief executive, said in a comment on Mr. Koum’s Facebook post that he would miss working with Mr. Koum.
“I’m grateful for everything you’ve done to help connect the world, and for everything you’ve taught me, including about encryption and its ability to take power from centralized systems and put it back in people’s hands,” Mr. Zuckerberg wrote. “Those values will always be at the heart of WhatsApp.”