Marcos R.

Full-Stack / Product Engineer with 6+ years building and shipping production software for startups and growing businesses. I've completed 26 jobs on Upwork with a 100% Job Success Score, Top Rated Plus status, and 3,400+ hours of work on the platform. I build products end-to-end. You can give me an idea, an existing application, or a business process that needs to be automated, and I can take care of the technical side from architecture to production. That includes the frontend, backend, database, mobile apps, third-party APIs, AI features, automations, integrations, deployment, and everything in between. I'm also comfortable working with existing systems rather than starting from scratch. If your product needs to connect with a CRM, payment provider, Whats-App, an internal API, an external SaaS, an AI model, a database, or a workflow in n8n, I can build the integration and make the pieces work together. ### What I work with **Frontend** * Vue.js 2/3, React, TypeScript * Quasar, Tailwind * Responsive web applications and PWAs **Backend & APIs** * Node.js, Express, NestJS * Python, FastAPI, Django * REST APIs, microservices and backend architecture **Mobile** * React Native * Flutter **AI & Automation** * AI agents and LLM integrations * RAG pipelines * LangGraph * n8n automation * LiveKit voice AI * AI-powered features for existing applications **Data** * PostgreSQL * SQL Server * Supabase * Database design and optimization **Infrastructure** * Docker * GitHub Actions / CI/CD * Playwright * Cypress * Production deployments ### What you get when you work with me **One engineer who can own the whole product.** I can design the architecture, build the database and APIs, develop the frontend or mobile app, integrate third-party services, add AI and automation, and take the application to production. **Strong Upwork track record.** 26 completed jobs, 3,400+ hours, 100% Job Success Score and Top Rated Plus status. I've worked with startups and businesses that needed someone they could trust to take ownership instead of just completing isolated tickets. **Integration-first mindset.** Modern products rarely live in isolation. I can connect your application to the systems you already use and build the glue between them — APIs, webhooks, SaaS platforms, AI providers, databases, automation workflows and internal systems. **Practical engineering.** I care about shipping software that solves the business problem, not adding technology for the sake of it. If an automation can eliminate manual work, I'll automate it. If an existing system can be integrated instead of rebuilt, I'll integrate it. ### Examples of projects I've worked on * E-commerce PWA built with Vue.js * Client management systems for financial transactions * Restaurant ordering platforms * AI and automation workflows * API and third-party service integrations * Real-time applications and backend systems If you already have a product, an idea, or a system that needs to be connected and automated, send me the details. I'll look at the problem from the product and technical side and tell you what I'd build, what I'd integrate, and how I'd approach it.