Slack - A messaging app for teams who see through the Earth!
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.
Skype - Stay in touch with your family and friends for free on Skype. Download Skype today to chat and call on desktop and mobile.
Chatib - Chatib is an online chat room where you can meet and chat with new people, make them friends, or even data them online.
RingCentral Video - Live life unlimited. Free video meetings and team messaging in one app that works the way you do.
Chattusa - Chattusa is a social network website that provides a free chat service and lets you connect with people from the USA without any hassle.