Seald - Keep your conversations secure, everywhere.
Signal - Fast, simple & secure messaging. Privacy that fits in your pocket.
Crypho - End-to-end-encrypted messaging and file sharing
Olvid - The most secure messaging app in the world.
Spike - Spike solves businesses' communication chaos by bringing together email, team chat, collaborative docs, and meetings, into one feed.
WireMin - WireMin is a private messaging tool for your most personal communications.