About me

Carlos Castelan

Senior Software Engineer · Backend, APIs & System Integrations

Building backend systems,
APIs & integrations

Software engineer with 6+ years designing backend systems, APIs, and integrations for large-scale enterprise applications. Built and shipped production REST/SOAP APIs, automated complex workflows with Python, and owned CI/CD pipelines end-to-end.
Strong foundations in Java, Python, and Node.js — looking to bring this backend and integration depth to a product-focused company.

Experience

Work experience

  1. SEP 2022 — PRESENT

    Senior Application Solution Developer (Software Engineering)

    Oracle · Puebla, Mexico

    • Designed and shipped production REST APIs with Spring Boot and Jersey, connecting a high-traffic procurement platform to multiple external services and enabling reliable cross-system data flows.
    • Embedded GenAI and conversational AI capabilities into existing backend systems, enabling natural language interactions and AI-driven automation on top of live production data.
    • Owned CI/CD pipelines end-to-end in Jenkins for both backend services and frontend apps, eliminating manual deployment steps and standardizing the release process.
    • Led a full-stack modernization of a core internal app — migrated the UI framework while preserving all backend integration contracts and keeping the system live throughout.
    • Designed data pipelines and reporting layers in SQL/PL/SQL that gave finance and operations teams real-time visibility into procurement data.
    Backend APIs Spring Boot Integrations CI/CD GenAI

  2. MAR 2020 — SEP 2022

    Application Solution Developer (Software Engineering)

    Oracle · Puebla, Mexico

    • Built and maintained REST and SOAP APIs with Spring Boot and Jersey, integrating internal modules with third-party systems across a multi-tenant enterprise platform.
    • Automated high-frequency data processing and API workflows with Python, replacing manual operations and reducing turnaround time on recurring tasks.
    • Built internal dashboards and audit tooling that surfaced backend data to finance and operations teams, reducing dependency on manual data requests.
    • Maintained production reliability across a complex enterprise platform — debugging API failures, data inconsistencies, and integration edge cases under live pressure.
    REST & SOAP APIs Python Automation Production Support

  3. AUG 2019 — FEB 2020

    Full Stack Developer

    Grupo JV · Puebla, Mexico

    • Designed and implemented a user-friendly web interface for an internal income management application.
    • Deployed and maintained applications on AWS, improving performance, reliability, and deployment processes.
    • Delivered end-to-end features with a focus on scalability, robustness, and maintainable code.
    Full Stack AWS Scalability

  4. JUN 2019 — AUG 2019

    Intern

    T-Systems México S.A. de C.V · Puebla, Mexico

    • Supported UX design and implementation for an Order Management web portal.
    • Assisted in defining server-side architecture and technical foundations for a web portal initiative.
    • Contributed to process improvements and technical documentation within the team.
    UX Architecture Process
Skills

Capabilities

Core strengths developed through building backend systems, APIs, and integrations at scale.

Backend Engineering

Design and ship production APIs and services with a focus on reliability, clean contracts, and long-term maintainability.

Integrations & APIs

Build reliable integrations across services — ensuring clean data flows, proper error handling, and observability end-to-end.

Automation & CI/CD

Automate workflows and deployment pipelines to eliminate manual steps and keep systems moving fast and reliably.

AI Integration

Embed GenAI and conversational AI capabilities into existing backend systems to extend automation and enable intelligent workflows.

Core Technologies

A snapshot of the stack behind my backend services, integrations, automation, and AI work.