I run toui.io, a URL shortener I shipped to the public on April 7, 2026. Eleven days before launch I had passwordless email login working on Resend. Five days before launch I tore it out and rebuilt the same flow on AWS — Lambda + DynamoDB + SES + API Gateway, packaged as a SAM stack.
The whole migration took one afternoon. I want to write about why I did it, what the stack looks like, and the one thing I'd do differently.
This isn't a Resend hit piece. Resend is excellent for product engineers who want clean DX, a great API, and to never think about deliverability. If you're shipping a side project, use it. The math just changes when you start projecting actual production volume.
The math that pushed me off Resend
When I shipped the Resend version on March 27 the price was $0/month — toui.io was a side project sending zero emails. Then I sat down and projected the year-one cost curve.
