Seald - Keep your conversations secure, everywhere.

Element.io - Secure messaging app with strong end-to-end encryption, advanced group chat privacy settings, secure video calls for teams, encrypted communication using Matrix open network. Riot.im is now Element.

Crypho - End-to-end-encrypted messaging and file sharing

Signal - Fast, simple & secure messaging. Privacy that fits in your pocket.

Spike - Spike solves businesses' communication chaos by bringing together email, team chat, collaborative docs, and meetings, into one feed.

Slack - A messaging app for teams who see through the Earth!