Based on Devup UI’s upcoming FEConf session, YoZm IT interviewed and published an article featuring the talk.

**Q. Hello! Please introduce yourself.**

Hello, I’m Jeongmin Oh, CEO of DevFive. I’m a developer-turned-founder, building various solutions and also running an SI business. I especially enjoy creating systems that reduce overhead and inefficiency—and I’ve tried a lot in that direction. When you spend a long time on something, you sometimes wonder, “Am I doing this right?” But seeing a system finally come together and work properly is so rewarding that I just can’t stop.

Above all, I love solving non-mainstream problems with technology. Not long ago, DevFive open-sourced Braillify, a Korean braille transcription library, and received a strong positive response. Technically, I’ve been deeply into Rust lately. Everything from Devup UI to Braillify—the topics I’ll be presenting at FEConf—was built on Rust.

**Q. What topic will you be presenting at FEConf 2025?**

If you’ve built React apps, chances are you’ve used CSS-in-JS. But when Next.js introduced RSC (React Server Components) and made it the default, the CSS-in-JS ecosystem took a major hit. Many attempts followed to solve this with Zero Runtime CSS-in-JS, but most results were only half-complete.

In my talk, “Truly ZERO-COST CSS-in-JS, Devup-UI,” I’ll introduce Devup UI—a fully complete CSS-in-JS library. I’ll share how it was built, the services already using it, and real coding outcomes. I invite you into the world of truly complete Zero Runtime CSS-in-JS.

Q. Pitch your talk!

I strongly recommend it to anyone interested in React apps and CSS performance optimization. I’m confident Devup UI is the solution that can optimize CSS completely. It’s also for those who love CSS-in-JS but have struggled with runtime dependency issues—and for anyone who’s suffered from bundling an enormous amount of CSS just to use a single component from a UI library. I believe you’ll find this session especially valuable.

Q. How do you feel about participating as a speaker?

Since I’m introducing a solution designed for top-tier performance, I’ll prepare thoroughly so I can share everything. I’ll be as generous as possible with my knowledge and experience!