sergio@dev — ~/portfolio

sergio@dev ~ % whoami

Sergio Márquez · AI Engineer · applied AI

I build agentic AI systems in production.

> cat ~/.now Agentic AI systems in production

> ls ./proof AI systems in production · 40+ open-source repos

  • Agentic RAG
  • Google ADK
  • Vertex AI
  • Claude Code
  • Python/FastAPI
  • GCP

~ % ls ./metrics --prod # impact in production

  • −75%
    processing cost
    GCP data platform: faster processing and orphan-document cleanup
  • 70 → 90%
    document validation
    Multi-LLM consensus (GPT + Claude + Gemini) with tuned OCR
  • −35%
    infrastructure cost
    Chat migration to agentic architecture with Google ADK + LiteLLM
  • 3.6M+
    records processed
    GCP data platform (medallion) with zero data loss

~ % cat about.md

From backend to building with agents

AI Engineer. I build AI systems that actually run in production: conversational assistants, smart search over documentation, and automated document validation. I work with LLMs, Python/FastAPI and GCP, with a backend, data and operations foundation so AI doesn't stay a demo. Results this past year: document validation from 70% to 90%, ~35% lower infrastructure cost, and ~75% lower data-processing cost. I use Claude Code daily and review with multiple models before critical changes. I measure in metrics, not demos.

I also run Esem Projects , an applied-AI agency for clinics in Spain.

~ % git log --oneline work/

Cases in production

VITALY · Full-Stack Developer
Jun 2021 – May 2025

Java/Spring backend leading GKE migration and CI/CD.

  • GKE
    led migration
  • 3 meses
    Dublin 2022
  • Strategic Middleware APIs: Designed and developed Spring-based middleware to optimize frontend/external services communication.
  • GKE Migration & Optimization: Led the migration to Google Kubernetes Engine, automating continuous delivery and optimizing deployments.
  • Post-Merger Data Integration: Actively participated in the data integration after the Preving/Cualtis merger, performing mapping and application adaptation.
VITALY · Intern Developer
Apr 2021 – Jun 2021
  • Received intensive training in Java Spring, Angular, Docker, and Kubernetes.
  • Participated in agile development teams, contributing to real-world projects and learning full software lifecycles.

~ % ls builds/

Things I've built

More on GitHub →

~ % cat signals.md

Where I share what I learn

~ % cat creds.md

Certifications & training