ChatSecure - ChatSecure is a free and open source messaging app that features OTR encryption over XMPP.
Z: Make Friends on Snapchat - Z: Make Friends on Snapchat is a useful app for meeting new people and building lasting relationships with them.
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.
ChatIW - Meet and Chat with new friends around the world.
Swiping – Make Friends - Swiping is a handy app that lets you Make Friends online.
Kandan - Open Source private chat server. Your own private Chat server in minutes, plus additional features.