ChatSecure

ChatSecure is a free and open-source messaging app for MacOS, which that features OMEMO encryption and OTR encryption. The app is not connected to a phone number or mobile phone address book, as it runs over XMPP. ChatSecure works with Google Hangouts, Facebook messaging, and other popular messaging services. When it is used together with Orbot, internet activities are also anonymized, making your online communications even more secure.