Whisper.sh - Whisper is the best place to express yourself online. Connect with likeminded individuals and discover the unseen world around you.
nocnoc - Instant group chat invite via link
Sayat - Sayat app is all about getting anonymous and honest feedback.
Viber Communities - Group chat with up to 1B members, admin controls and more
Sarahah - Sarahah is a Social Networking Application for providing anonymous feedback launched in 2016 and available to use on iOS and Android platforms.
Public - Group chats.