WhatsApp wasn't originally a product from Facebook. They bought it in 2014 and the article I found about them fully launching end-to-end encryption in 2016 says

WhatsApp wasn't originally a product from Facebook. They bought it in 2014 and the article I found about them fully launching end-to-end encryption in 2016 says that it was in rollout for the prior year on various platforms, which would imply they had already been working on it before that; I've always understood it to be a thing that Facebook took seriously pretty quickly after getting WhatsApp. https://threatpost.com/whatsapp-adds-end-to-end-encryption-to-one-billion-users/117213/ https://threatpost.com/whatsapp-adds-end-to-end-encryption-t... > “Over the past year, we’ve been progressively rolling out Signal Protocol support for all WhatsApp communication across all WhatsApp clients. This includes chats, group chats, attachments, voice notes, and voice calls across Android, iPhone, Windows Phone, Nokia S40, Nokia S60, Blackberry, and BB10,” wrote Open Whisper Systems founder, Moxie Marlinspike.