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.

This episode is brought to you by:

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🔑 Key Lessons

📊 The Mandatory Survey: Why forcing users to answer questions during signup actually helped growth without hurting conversion.
🚪 The "Fake Door" Test: Validating a major feature (Email Campaigns) with a dummy button before building it.
💰 Monetization: Transitioning a free community tool into a profitable recurring revenue business using data-driven pricing.
🛠️ Developer Marketing: How to build a product that developers naturally share (PLG) without a sales team.
🔄 The Pivot: How they navigated the risky shift from blocking emails to sending them reliably in production.

📖 Chapters

The 20,000 Email Disaster (Origin Story)
Building Internal Tools: The "Eat Your Own Dog Food" Strategy
The Decision to Monetize a Free Tool
Pricing Strategy: Using Data & Interviews to Find the Price
The Onboarding Myth: Why Fewer Clicks Didn't Increase Conversions
The Mandatory Signup Survey (That Didn't Kill Growth)
The "Fake Door" Test: Validating Email Campaigns Before Building
The Pivot: Expanding from Email Testing to Email Sending
Competing with Giants (SendGrid, Mailgun)
AI for Developers: Hype vs. Reality

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Resources

Full show notes: https://saasclub.io/456
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Miércoles 29 enero – Marcos 4, 1-20. Salió el sembrador a sembrar.