Whisper.sh - Whisper is the best place to express yourself online. Connect with likeminded individuals and discover the unseen world around you.
Viable Fit - Measure and improve your product market fit
Sayat - Sayat app is all about getting anonymous and honest feedback.
Startup Growth Roadmap - Get from idea to product market fit
Sarahah - Sarahah is a Social Networking Application for providing anonymous feedback launched in 2016 and available to use on iOS and Android platforms.
Focus Framework - A hands on guide to find product-market fit w/ lean methods