Hey, I’m Demóstenes. Just call me Demo
Complex web & mobile products, made accessible and built to last.
Senior product engineer. 15+ years shipping React, Next.js and React Native products used by millions.
Results
- 600K+
- members on a healthcare platform moved to React without a feature freezeCollective Health
- 500 to 0
- critical and high accessibility findings, verified with real screen readersCollective Health
- −70%
- UI bugs in two quarters, with a design system 5 teams adoptedProductPlan
Trusted atCollective HealthProductPlanBank of AmericaAmex
Selected work
Things I’ve built.
- Open source · Design system
Mola UI
A React design system for AI interfaces and dense internal tools.
68 components and tokens
- Mobile & web app
Polla Mundialista
A bilingual, social score-prediction game for the 2026 tournament.
iOS, Android and the web
- Public health
Cerco Solidario
Bluetooth contact tracing for Panama, private by design.
Featured on TVN Noticias
Outcomes
What changes when I join.
Web and mobile, one engineer.
React and Next.js on the web, React Native on iOS and Android: one product, one owner.
Full stack, front to back.
From Rails APIs and data models to the screen people tap, with no hand-offs in between.
Product first, then code.
I start from the user and the problem, and help decide what to build, and what not to.
Releases stop being a gamble.
Tests, reviews and a steady pace, so every launch ships with confidence.
Accessibility is part of the equation.
WCAG 2.2 from the first sketch, verified with JAWS, NVDA and VoiceOver.
The interface stops drifting.
Design systems a team actually reaches for, on web and mobile alike.
Let’s build your next project.
Tell me what you’re building. I usually reply within a day.
Start a conversation