SafeNote - Encrypt and send files and notes with a link that automatically destruct after being read. SafeNote is a free web-based service that allows you to share a note or a file with confidentiality. There is no way to spying on you even to a hacker.
FluffyChat - Open. Nonprofit. Cute ?
Privnote - Send notes that will self-destruct after being read
Signal - Fast, simple & secure messaging. Privacy that fits in your pocket.
Revealit.me - ReveaiIt.me allows you to send a one time link to a self-destructing document.
Molly (Signal fork) - Molly is an independent Signal fork for Android