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ludinecg/README.md

Ludin Castillo

Data Engineer · BI Specialist · SQL Server expert in financial systems


About

I'm a data engineer with nine years of hands-on experience in the financial sector, most of it spent inside the SQL Server stack of a Guatemalan bank — moving data, breaking down stored procedures, designing dashboards, and chasing down the kind of integrity issues that only show up after the report has already gone to a VP. I care about correctness more than novelty, and I tend to ask "what does the execution plan say?" before I ask "what does the framework do?".

These days I'm pushing further into Python, AWS, and AI quality evaluation. The portfolio you see below is the public version of the work I used to do behind a corporate firewall — same techniques, on synthetic data, fully reproducible.

Based in Guatemala City (GMT−6). Comfortable working with teams across the Americas and Europe. Open to remote Data Engineer / Analytics Engineer / BI roles — full-time, contract, or freelance.


Tech I work with

SQL Server T-SQL Tableau Power BI Python Pandas Flask Docker AWS Postman Git

What I'm strongest at: query optimisation, stored procedures, indexing strategy, data quality frameworks, and translating messy business requests into useful BI deliverables.


Featured projects

Project What it shows Stack
financial-sql-optimization Full SQL tuning cycle on a 1M-row financial dataset. Logical reads cut by 75–99% on three of four benchmark queries. SQL Server 2022, Docker, Python
data-validation-api REST API for transaction validation. Designed to plug into upstream data pipelines and reject bad records early. Python, Flask, Docker, Render
financial-analytics-dashboard (coming) Tableau Public dashboard built on the same dataset — KPI cards, time-series, heatmap by hour/weekday. Tableau Public
ai-quality-evaluator (coming) Framework for evaluating LLM responses across accuracy, completeness, and hallucination risk. Python, OpenAI API

Currently

  • Studying for the AWS Certified AI Practitioner exam (target Q3 2026).
  • Levelling up Python from automation scripts into proper data engineering work (Pandas, Flask, eventually dbt).
  • Improving English (B2, working on it at university). Spanish is my native language.

GitHub stats


Sobre mí (ES)

Soy ingeniero de datos con nueve años en el sector financiero, casi todos dentro del stack de SQL Server de un banco guatemalteco — moviendo datos, desarmando stored procedures, diseñando dashboards y rastreando ese tipo de problemas de integridad que sólo aparecen cuando el reporte ya llegó a un VP. Me importa más la corrección que la novedad, y suelo preguntar "¿qué dice el plan de ejecución?" antes que "¿qué hace el framework?".

Actualmente estoy expandiendo mi stack hacia Python, AWS y evaluación de calidad de IA. El portafolio que ves arriba es la versión pública del trabajo que solía hacer detrás de un firewall corporativo — mismas técnicas, sobre datos sintéticos, totalmente reproducibles.

Vivo en Ciudad de Guatemala (GMT−6). Trabajo con equipos en América y Europa sin fricción. Disponible para roles remotos de Data Engineer, Analytics Engineer o BI — tiempo completo, contractor o freelance.


Updated May 2026

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  1. financial-sql-optimization financial-sql-optimization Public

    End-to-end SQL Server 2022 tuning on a 1M-row financial dataset: indexes, query rewrites, data integrity. Logical reads cut 75-99% on three of four benchmark queries.

    TSQL

  2. ludinecg ludinecg Public

    I'm Ludin Castillo