CoverMe - Private texting, calling, vault
Keybase Chat - End-to-end encrypted chat built into Keybase
Messenger Platform - Discovery, chat extensions, and richer experiences
Spike - Spike solves businesses' communication chaos by bringing together email, team chat, collaborative docs, and meetings, into one feed.
Facebook Messenger Kids - Safer and More Fun Video Calls and Messaging
Seald - Keep your conversations secure, everywhere.