Dan Castrillo

Hi, I'm Dan — a Senior Software Engineer with 10 years building production systems across the full stack. Currently at Upwork, where I architect frontend experiences and pioneer AI-driven development workflows. Based in Spain.

I'm a polyglot engineer fluent in TypeScript, React, Vue, Next.js, Python, Go, and Odin. I've shipped billing systems, real-time calendars, computer vision pipelines, and PEG parser compilers. When I'm not at work, I build tools in Odin and write about systems programming.