Back in 2011, Sergiy Korolov's team accidentally sent 20,000 test billing emails to real customers—a complete disaster. They built a simple internal tool to prevent it from happening again, shared it with the Ruby on Rails community, and it exploded. Fast forward to today: Mailtrap generates seven-figure ARR with 100,000+ monthly active users.

In this episode, Sergiy Korolov (Co-founder of Mailtrap) reveals the SaaS Pricing Strategy behind converting a massive free user base into paid customers. Learn his controversial "Mandatory Survey" tactic that unlocked deep customer insights without hurting conversion, how he used a "Fake Door" test to validate a massive product pivot before writing code, and the specific challenges of expanding from a simple testing sandbox into a full-scale Email API platform.

In this episode, Sergiy also explains why simplifying onboarding didn't increase conversions (and what that revealed about developers), the "Eat Your Own Dog Food" strategy that fueled their initial growth, and how to compete with giants like SendGrid by focusing on developer experience.

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