Luis Castro

Andorra-based full stack engineer with 14+ years of experience.Andorra-based full stack engineer with 14+ years of experience. The products I've helped build have reached millions of people around the globe, from ride-hailing platforms to celebrity marketplaces to content discovery apps. I architect for scale, business growth, and developer experience, because I believe great products come from the place where design quality and engineering rigor meet. I thrive in fast-moving teams, and I bring a track record of shipping products that users love and businesses rely on. I'm a TDD fanatic, and I'm having a blast using AI to sharpen my thinking process so we can build well-considered, business driven experiences.

Cameo, Andorraluiscastro.co castrolem

Interests:

react javascript node.js code quality architecture typescript fullstack performance state management scalability team productivity

Rebuilding a 7-Year-Old Marketplace From the Architecture Up

React Day Berlin 2026

Upcoming

Rebuilding a 7-Year-Old Marketplace From the Architecture Up

We built a successful marketplace over the past 7 years. 50+ engineers left their mark on the codebase, and most of them are no longer with the company, so every time we looked under the hood, we were afraid. AI made the problem less noticeable for a brief moment, and then we hit the wall. Every update any team shipped made our React app feel more sluggish, harder to maintain, and impossible to upgrade. We were stagnating, and the frustration across product, management, and engineering kept growing.

So we went back to the drawing board to understand what made our business successful in the first place, peeling back the layers and focusing on the domains we actually wanted to invest in.

This talk dives into how we rebuilt from the ground up with a completely new lens on how we architect features. I'll break down the patterns, the research, and the lessons we learned along the way.

architecture