8 secure encrypted messaging and video call apps (2021)
Comparison of messaging and VOIP services: Signal vs Telegram vs Threema vs Wickr vs Wire vs Element vs Keybase vs twinme
Keybase
Keybase is a fully encrypted Slack-like Messenger. Keybase is a an open-source chatting application for computers and mobile phones and it is powered by public-key encryption.
Warning: Keybase is no longer recommended since is it now owned by Zoom with deep ties to China (privacy concerns).
More info: https://keybase.io