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Mario Araya Romero

@marioarayaromero

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Senior full-stack engineer building end-to-end SaaS with production AI workflows and clean architecture.

Chile

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What I'm looking for

I’m looking for a team where I can own end-to-end SaaS delivery, integrate production AI/LLM workflows (context, decomposition, quality gates), and improve observability and CI/CD—while keeping architecture clean and moving fast without needing a large team.

I’m a senior full-stack engineer with 15+ years shipping production software across fintech, retail, and healthcare. I build end-to-end SaaS products fast, with clean architecture and without a large team, and I lead where it matters—architecture decisions, observability, and engineering process improvements. At Fresenius Kabi, I designed and integrated a full LLM workflow into the engineering process (context architecture, agent task decomposition, quality gates), reducing delivery time ~30%.

In my day-to-day work, I use the Claude API, Claude Code, and GitHub Copilot to multiply feature delivery, and I understand AI agent observability from the inside—trace inspection, version comparison, and failure analysis as a practitioner. My stack spans React/Next.js/TypeScript and backend systems in Python (Flask, FastAPI), Node.js, and Java/C#/.NET, plus production infrastructure with Azure and GCP, CI/CD, and robust testing (Playwright, Cypress, Jest/JUnit). I write things down, work async-first, and build systems other engineers can extend.

Experience

Work history, roles, and key accomplishments

Current

Full-Stack Engineer & Tech Lead

Current

Fresenius Kabi

Jun 2025 - Present (1 year)

Integrated Claude API into the team's daily engineering workflow and designed an end-to-end LLM agent workflow (context architecture, task decomposition, quality gates), reducing delivery time ~30%. Built Azure DevOps CI/CD and Docker-based pipelines, cutting deploy time ~60%, and led microservices/observability decisions with Grafana/Prometheus while improving frontend performance with Playwright

Claude Claude Code Azure DevOps Docker Microservices Grafana Prometheus Playwright React Typescript

Fullstack Java Engineer

BTG Pactual

Sep 2024 - Mar 2025 (6 months)

Built scalable REST APIs in a high-criticality Java codebase using Maven, Oracle 11g, Hibernate, and WebLogic, achieving ~80% code coverage with JUnit and Cypress. Produced full OpenAPI/Swagger documentation and collaborated with business teams to translate requirements into technical specifications.

Java REST APIs Maven Hibernate Oracle Weblogic Junit Cypress Specifications

Fullstack Go Engineer

Banco Ripley

Sep 2023 - Apr 2024 (7 months)

Designed and built an Apple Pay integration for a PWA using Go with hexagonal architecture on GCP (Cloud Run, Cloud SQL). Implemented webhook/event-driven async flows with retry/idempotency strategies and delivered CI/CD via GitHub Actions.

Go Hexagonal Architecture Cloud SQL Webhooks Async Flows CI CD

Fullstack Java + React Eng

Walmart (Lider.cl)

Dec 2020 - Jan 2023 (2 years 1 month)

Built full-stack capabilities for a high-traffic retail environment using Java 17 Spring Boot 3, Kafka, Redis, React, and TypeScript, improving load time by ~20%. Developed micro-frontends using Module Federation and partnered with product, ops, and non-technical stakeholders to define requirements and integration specifications.

Spring Boot Kafka Redis React TypeScript Module Federation Performance Optimization

Fullstack .NET + Angular Eng

Banchile Inversiones

Aug 2018 - Jul 2020 (1 year 11 months)

Developed REST APIs with C# .NET Core (OpenAPI/Swagger) and built an Angular frontend. Supported legacy system migration to modern architecture and handled delivery with GitLab CI/Jenkins and Cypress testing.

C# .NET Core REST APIs Angular Gitlab CI Jenkins Cypress Frontend Development API Development

Frontend Engineer

Globant

Nov 2017 - Jun 2018 (7 months)

Built React components for a ticket purchase flow for LATAM Airlines using TDD with Selenium, Mocha, and Chai. Implemented analytics with Splunk and Google Analytics.

React Selenium Mocha Chai TDD Analytics Splunk Google Analytics

Fullstack .NET Engineer

Inversiones Security

Oct 2015 - Nov 2017 (2 years 1 month)

Developed REST APIs using C# .NET Core and an Angular frontend, including real-time price tracking fed by Bloomberg and Santiago Stock Exchange APIs. Built proofs of concept with Node.js/Express.

C# .NET Core REST APIs Angular Bloomberg API Santiago Stock Exchange APIs Node Express Proofs Of Concept Frontend

Fullstack .NET + Java Eng

Huenei / BTG Pactual / Penta

Jun 2012 - Aug 2015 (3 years 2 months)

Worked on mutual.cl and chilecompra.cl integrations and legacy migrations using C#, REST, SOAP, and SQL Server. Delivered SOA integrations across enterprise systems.

C#REST SOAP SQL Server SOA Integration Backend Development

SmartTV & Mobile Developer

Fusiona

Jun 2011 - Aug 2012 (1 year 2 months)

Built and published a Samsung SmartTV app for TVN Chile using the Samsung SDK and JavaScript, released on the Samsung Smart TV App Store. Also developed an RSS/weather app for Windows Phone and contributed to CMS-based sites for Nestlé and St. George's College.

JavaScript Smart TV App Store Publishing RSS Weather App CMS Development Cross Platform Development

Fullstack .NET Engineer (SOA)

CGE

Dec 2008 - Jan 2011 (2 years 1 month)

Implemented SOA/DDD architectures integrating SAP via REST/SOAP using the Spring Framework. Built SQL Server-backed services with unit testing and performance optimization.