Senior Full-Stack Engineer
Building scalable SaaS products across web, mobile, and backend systems

Full-Stack Engineer with 7+ years of experience building production software used in real-world environments.

I work across the full stack, including:

• Frontend (React, Next.js)
• Mobile (React Native)
• Backend (Node.js, Prisma, PostgreSQL)
• Infrastructure (Docker, background jobs with BullMQ)

Currently focused on SaaS and fintech systems, including compliance-related backend services and product-driven platforms.

Full-featured internal system designed to manage business operations, logistics, and workflows, built for real client usage with a focus on reliability and scalability.

End-to-end SaaS platform for event creation, ticket sales, and attendee management, including payment flows and check-in systems.

Product-oriented platform supporting stock tracking, product management, and operational workflows across business entities.

Real-time multiplayer game built with Socket.IO, featuring synchronized rounds, scoring, and event-driven architecture.

• Building and maintaining production-grade SaaS systems
• Designing clean and scalable architectures
• Delivering features across frontend, backend, and mobile
• Improving existing systems through refactoring and performance work
• Supporting real-world systems and solving operational issues

Frontend

• React
• Next.js
• TypeScript

Mobile

• React Native

Backend

• Node.js
• Prisma
• REST APIs
• Microservices

Database

• PostgreSQL

Infrastructure

• Docker
• BullMQ

Remote opportunities (EU)
SaaS / Fintech / Product companies

• Portfolio → https://kingdevil731.dev
• LinkedIn → https://www.linkedin.com/in/ruben-folhento
• GitHub → https://github.com/kingdevil731