How I Built a High-Performance SMS Verification Service with Rust and Axum

I built SMSCode because I was frustrated with existing SMS verification services. Overpriced, slow OTP delivery, terrible APIs, and documentation that looked like it was written in 2010. So I rewrote everything from scratch in Rust. The Problem If you've ever tried to automate SMS verification — for testing, privacy, or bulk operations — you know the pain. Most services charge $0.50+ per number, have APIs that randomly fail, and support maybe 50 countries if you're lucky. I needed something better. The Stack Backend : Rust with Axum framework Frontend : Astro SSR Database : PostgreSQL + Redis Infrastructure : Bare metal servers on Proxmox Why Rust? Performance and reliability were non-negotiable. With 100K+ active users making real-time requests, I needed something that wouldn't buckle under load. Architecture Overview The system follows a domain-driven design with clear separation between: Number inventory management — pooling numbers across multiple providers Order processing — idemp