Full Stack Developer · Berlin

Mauricio
Rojas

Building reliable, user-focused software: from AI-powered tools to full stack web apps. 7+ years solving complex problems at scale, now shipping code.

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About

Finally on the right
side of the terminal.

After 4+ years solving complex technical problems at Klarna — one of Europe's leading fintechs — I made the deliberate move into software development. I completed an intensive AI Web Development Bootcamp at Ironhack and have been shipping production apps ever since.

I bring an unusual combination to engineering teams: the craft of a developer and the operational instincts of someone who's worked inside fast-moving, cross-functional tech organisations at real scale.

I'm particularly drawn to products where reliability and user experience intersect and to teams that take ownership seriously.

Location Berlin, Germany
Languages Spanish (native) · English (C1) · German (B1)
Currently Open to Junior / Full Stack roles in Berlin
Education Ironhack AI Web Dev Bootcamp · 2026
Stack React · Node.js · TypeScript · MongoDB · AI APIs

Skills

Languages

JavaScript (ES6+) TypeScript

Frontend

React HTML5 CSS3 Responsive Design

Backend

Node.js Express.js REST APIs

Data

MongoDB Mongoose

Tools

Git GitHub Vite JWT Cloudinary

AI Tools

Claude API OpenAI API Cursor

Projects

AI Node.js LLM REST API

Sales Analyst Agent

AI agent built with the OpenAI Responses API that lets users upload sales reports and ask questions through a chat interface. Uses the file_search tool with vector stores for document retrieval. Full stack in Python and Flask, deployed to production on Render.

Hosted on Render — may take ~30s to wake up

Open project
React Node.js MongoDB JWT Cloudinary

nestmate

Full stack MERN platform to find compatible roommates and shared housing. Features auth, real-time messaging, image uploads, apartment listings, and filtering — deployed to production on Vercel.

Open project
React Vite Discogs API CSS

SpinSoul

Music rating dashboard integrating the Discogs API (500k+ releases). Search, favourite, and rate albums in a clean, responsive interface focused on component architecture and API integration.

Open project
React TypeScript Node.js PostgreSQL Prisma Google OAuth

Workout Tracker

Full stack fitness app to plan training weeks, log exercises with sets, reps and weight, and track progress automatically. Built with React + TypeScript on the frontend, Node.js + Express + Prisma on the backend, PostgreSQL for data persistence, and Google OAuth + JWT for authentication.

Open project

Experience

2021 — 2025 Klarna AB Berlin, Germany

IT Engineer — Device and Tech Operations Team

  • Operated within cross-functional engineering teams at a global fintech, collaborating with software, security, and product teams to deliver reliable solutions at scale.
  • Redesigned onboarding workflows end-to-end, cutting setup time by 60% — owning the problem from diagnosis to delivery and ongoing monitoring across DACH and US regions.
  • Drove documentation improvements that reduced first-line resolution time, demonstrating systems thinking and a bias for continuous improvement.
  • Partnered with security and compliance teams on access reviews and device hardening initiatives.
2017 — 2019 Vitamina Santiago, Chile

IT Support Engineer

  • Supported internal users across multiple sites and maintained reliable day-to-day IT operations.
  • Improved service consistency through KPI tracking, process organization and proactive issue resolution.
  • Coordinated with different stakeholders to deliver practical technical solutions in business settings.

Contact

Let's build something together.

I'm currently open to Junior Software Engineer roles and freelance projects in Berlin. If you're working on something interesting, I'd love to hear about it.

Email me LinkedIn GitHub