Pavel Durov
Pavel created two leading tech companies. In 2006 he founded VKontakte, the most popular social network in Russia, Ukraine and Belorussia. In 2013 Pavel launched Telegram, a messaging platform focused on privacy and security. Telegram attracted o...
https://youtu.be/_2ObY0xBm5A
Signal is one. Here's a few more
Signal has a backdoor tho its been known for a while, one that ive come across seems to be toxchat, it doesnt have an actualy standard client across all platforms but has a list of clients that work and they support, currently its doesnt support ios but does macos https://tox.chat/
Heres the rest on that youtube link I posted:
Signal Messenger https://play.google.com/store/apps/de...
Element https://play.google.com/store/apps/de...
ToxChat Clients Phone Client https://play.google.com/store/apps/de... Desktop Client https://github.com/qTox/qTox/releases...
Wickr Me https://wickr.com/me/ https://play.google.com/store/apps/de...
Threema https://play.google.com/store/apps/de...