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.
Slackmojis - A directory of the best custom slack emojis
ChatSecure - ChatSecure is a free and open source messaging app that features OTR encryption over XMPP.
Mojirater - Emoji reactions & social share buttons for your site
Keybase Chat - End-to-end encrypted chat built into Keybase
EMOJI.RODEO - Slack's reactions on your site