Resend Found Software Agents Break on Sleek Design
Resend founder Zeno Rocha explains why autonomous AI agents need RFC rate limits, OpenAPI JSON in well-known paths, and granular API scopes.
Building what's next (Interview)
With Adam Stacoviak, Zeno Rocha · Sunday, October 25, 2026
Adam Stacoviak speaks with Resend founder and CEO Zeno Rocha about scaling an email platform to three million users and one hundred thousand paying customers. They explore the hidden architectural rewrite from Node.js to Go to handle batch concurrency, building infrastructure optimized for AI agents through standardized RFC rate limits and markdown endpoints, and defending free developer tiers against coordinated spam gangs.
Key takeaways
- Resend scaled to three million users and 100,000 paying customers by sweating micro-interactions, but autonomous agents ignore the design details human developers love. Read more →
- Resend reached 100,000 paying customers out of 3 million total registered accounts while keeping its free developer tier intact. Read more →
- Resend discovered that Claude and ChatGPT were telling prospective buyers the platform was the most expensive email service on the market, despite offering competitive rates. Read more →
3 articles from this episode
Why Resend Refuses to Kill Its Free Developer Tier
Zeno Rocha faced organized spam gangs attacking Resend. Instead of killing the free tier, he used daily quotas to build 100,000 paying customers.
Why AI Models Kept Calling Resend the Most Expensive Email Service
Zeno Rocha explains how Resend fixed Claude and ChatGPT misquoting its pricing by serving static markdown and llms.txt files.
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