I design your product. Then I build it.
Full-stack engineer and trained designer. React and Next.js up front, Python and Node behind, PostgreSQL underneath. Remote from Paraguay for US teams since 2021.
Taking new projects · Luque, Paraguay · UTC-3
Hi, I’m Sergio
Own SaaS · in production
Welcomy: a SaaS I built alone.
Queue management for branches. Multi-tenant, with an AI router across Claude, Gemini and a local model, on infrastructure I run myself.
Your turn, on your phone
Clients and brands
Worked with
Brands and sites
“Strong technical execution and a real eye for design. He built our onboarding and referral processes, which were genuinely complex. I’d hire him again without hesitation.”
What I can do for you
- Build your productFrom schema to production: backend, frontend, infra and deploy. One engineer, end to end.Welcomy · Hilagro
- Join your teamA senior engineer inside your codebase and your process.Ooma · FlowEQ · ForFounder
- Design to codeFigma screens, design systems and mobile apps, built by the person who designed them.PlaceAnalyzer · Mi Sitio UP
- AI & automationLLM features with fallbacks, integrations and bots that remove manual work.Welcomy AI · Hilagro bot
Built and running
All work- WelcomyQueue management SaaS, from schema to productionBuilt solo, running live
- Universidad del PacíficoIntranet and apps used by every student and teacherWeb, iOS and Android
- HilagroSupplier and accounts-payable portal for agribusinessInvoices match themselves
- BuscoPetQR pet tags and the platform behind themScan the tag, call the family
Designed by the same hands
Forever FitDesign + build 
InitiativeDesign + build 
Monitor GPSDesign + build 
ProcardDesign 
Yo te llevoDesign
Also open source: TypeLang · WordPress Playbook · Builderdash
Working with me is simple: you see the design first, it ships in small slices, and one person answers for all of it.
Design first
Screens and flows before code, so you approve something you can see.
Small slices
Production deploys from the first weeks, CI on every change.
One person accountable
Schema, API, UI and infra.
Your hours
UTC-3, full overlap with US Eastern.
“An exceptional ability to craft intuitive interfaces, making complex features look effortlessly simple.”
Have a product in mind?
Tell me what you’re building. I usually reply within 1–2 business days.