Crypho - End-to-end-encrypted messaging and file sharing
Seald - Keep your conversations secure, everywhere.
blockslack.io - Chat for small teams — encrypted and decentralized
Brie.fi/ng - Start secure group video chat
Wire by EY - A highly secured collaboration platform
Spike - Spike solves businesses' communication chaos by bringing together email, team chat, collaborative docs, and meetings, into one feed.