once fyi - Create privacy friendly one-time mailing lists
NewsWhip - Chrome extension that checks how viral your content is
Best Referral Programs - A curated directory of startup referral programs
Promo Self Serve - Launch a promotion across the internet in 90 Seconds
Viral Loops for Startups - Virality for startups made easy 💪
Viral Coefficient Calculator - Calculate a viral referral loop for apps