The Serval Mesh - It works by using your phone's Wi-Fi to not communicate with other phones on the same network.
Whisper.sh - Whisper is the best place to express yourself online. Connect with likeminded individuals and discover the unseen world around you.
Briar - Secure messaging, anywhere
Sayat - Sayat app is all about getting anonymous and honest feedback.
WorldChat - Meet new people around the World on WorldChat.tv, the Original World Chat since 2011.
Stupid Chat - World's newest Anonymous Social Network