4. Delta Chat

Delta Chat is a secure, private communications tool, and it's really fast to create an account (and as many accounts as you want!), and it has the same interface across all platforms. Messages are encrypted between contacts by default (in fact, unencrypted messages aren't allowed to be sent out.)

Simply download Delta Chat and go to my server to create an account! No need to ask for permission you can make as many accounts as you want.