Senior Software Engineer - Java/.NET + AI

Óscar Calles Sáez

Senior Software Engineer who turns AI-generated implementations and

architectural alternatives into validated, maintainable software.

La Legua • Toledo, Spain • 45005 +34-617-**-**-** ️ *******@*****.***

linkedin.com/in/oscar-calles ️ docx ️ pdf pdf BIO

Highly driven Senior Software Engineer Java/Spring Boot + .NET/Angular Legacy Modernization AI-Assisted & Agentic Development with over 11 years of experience in full- stack development, backend systems, and mobile applications. I work at the intersection of engineering judgment and agentic development: AI agents propose implementations and architectural alternatives, while I validate trade-offs, maintainability, performance, and alignment with team standards. This human-led validation model has reduced feature delivery time by approximately 30% while keeping technical debt under control. SKILLS

Languages: Java, TypeScript, JavaScript, C#, Python (learning/fast adoption), Objective-C Frameworks: Spring Boot, Angular 17, .NET Core, Spring MVC, WPF, Entity Framework, LINQ, J2SE, J2EE

Cloud & Infra: GCP (certified), Terraform, Docker, Azure, CI/CD (Azure DevOps, GitHub Actions) AI/Agentic: GitHub Copilot Pro, agentic workflows, MCP (Model Context Protocol), AI-assisted code review, automated commit messaging, Cline integration Security: OAuth2, OpenID, JWT, Spring Security

EDUCATION

Bachelor Degree in Computer Science – Universidad Nacional de Educación a Distancia

(UNED), Graduated 2007

EXPERIENCE

Backend: Java 11 / Spring Boot Frontend: Angular 17 Digital Transformation Agency – Regional Government of Castilla-La Mancha 04/2025 – Present

Java 11 • Spring Boot • Angular 17 • OAuth2 • RxJS • NgRx • Docker • GCP

.NET Software Developer, Full Stack Accuro Spain 06/2023 – 04/2025

.NET 7 • Angular 15 • xUnit • Moq • Azure DevOps

.NET Software Developer, Full Stack UST Spain 12/2021 – 04/2023

.NET • Angular • REST APIs • OAuth2

.NET Software Developer Castilla-La Mancha Media 12/2015 – 11/2021 WPF • .NET • JavaScript • Python

iOS Developer Gwella 10/2015 – 12/2015

iOS • Objective-C • REST

iOS Developer Buzinger 03/2015 – 09/2015

Leading development of a new enterprise-grade digital services platform using Java 11, Spring Boot, and Angular 17.

Designed and implemented RESTful microservices with Spring Data JPA, Spring Security, and OAuth2 authentication.

Built responsive, component-based frontends with Angular 17, using RxJS, reactive forms, and NgRx for state management.

Integrated GitHub Copilot Pro to accelerate coding, generating descriptive commit messages and maintaining a docs.md file with every architectural change.

Extended AI capabilities by designing a Docker-based MCP gateway that centralizes GitHub, SonarQube, SQL, Keycloak, and browser automation tools into a unified local endpoint layer, enabling Cline and similar agents to invoke specialized services without exposing credentials.

Evolved the development process to an agentic mode, where the AI agent proposes code implementations and architectural variations, while I review, validate, and select the best approach based on performance, maintainability, and team style guidelines.

Reduced feature delivery time by ~30% compared to traditional coding, while keeping technical debt under control through continuous validation and manual oversight.

Collaborated with product owners and QA to align deliverables with business requirements and non-functional goals (scalability, security, observability).

Public sector government migration project using .NET 7 and Angular 15.

Modernized legacy modules, refactored business logic, and implemented new micro-frontends.

Improved test coverage with xUnit and Moq, and ensured CI/CD pipelines with Azure DevOps.

VMware migration project using .NET and Angular (12/2021 – 07/2022).

Developed backend APIs and integrated with external authentication systems. Built internal tools using WPF, .NET, console applications, Windows scripting, JavaScript, and Python.

Maintained and improved legacy systems, reducing response times by 20%.

Developed a health-sector iOS application with Objective-C and REST APIs. iOS • Objective-C • J2EE • SQL • Angular • Spring MVC COURSES & CERTIFICATIONS (2022–2023)

Udemy

Pluralsight

Created an indoor beacon-location iOS app.

Also contributed to J2EE, SQL, Angular, and Spring MVC projects.

Agile Fundamentals (Scrum & Kanban)

Blazor Bootcamp – .NET 6 E-Commerce (WASM & Server)

ASP.NET Core + Angular from Scratch

Building Microservices with ASP.NET Core 5.0 and Docker

Git Mindset – Underlying Architecture

Google Cloud Developer – GCP Professional Certification Microservices Architecture – Complete Guide, Implementation on .NET 5, Designing Highly Scalable Systems, Observability & Resilience

Secure .NET Microservices with IdentityServer4, OAuth2, OpenID

SQL for Beginners (MySQL & Database Design)

Terraform Beginner to Advanced (GCP)

The Complete Node.js Developer Course (3rd Edition)

English Grammar Launch

Arquitectura de Aplicaciones Empresariales con .NET 7

Object-Oriented Programming Fundamentals in C#

Developing with .NET on Azure – Getting Started

.NET 6 First Look

Regular Expressions

Cross-platform SQL Server Management for Developers (VS Code)

Using IIS 10 as a Developer

Angular 11 Fundamentals, Getting Started, NgRx, Reactive Forms, Routing, Component Communication, RxJS, Unit Testing (Angular 12)

Mocking with Moq and xUnit

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