Element.io - Secure messaging app with strong end-to-end encryption, advanced group chat privacy settings, secure video calls for teams, encrypted communication using Matrix open network. Riot.im is now Element.
Encrypto - Encrypto lets you encrypt files before sending them to friends or coworkers.
ChatSecure - ChatSecure is a free and open source messaging app that features OTR encryption over XMPP.
VeraCrypt - VeraCrypt is a free open source disk encryption software for Windows, Mac OSX and Linux.
Keybase Chat - End-to-end encrypted chat built into Keybase
TrueCrypt - TrueCrypt is a leading cross-platform that provides encryption tools that allow you to migrate any encrypted data to virtual disks images on your systems.