Resume · Barcelona, Spain

Daniel Diaz Diaz

Software Engineer · Java Backend

dan1@hotmail.es +34 655 803 158 linkedin.com/in/danidiazdiaz github.com/danidiazd

Software Engineer specialised in Java backend: microservices and REST APIs for banking, built on distributed architectures with IBM Host/Mainframe integration and batch processing. 250+ certified training hours in Java, databases, Clean Code and AI-assisted development.

CV en español View portfolio

Professional profile

Java Backend Developer with hands-on experience building RESTful microservices and enterprise APIs. Currently working in the banking sector, delivering solutions on distributed architectures, integrating with IBM Host/Mainframe systems and running batch processes (Java 8/11, Spring Boot, Oracle SQL, Docker). Experienced with SQL and NoSQL databases and robust authentication (JWT, OAuth2).

Beyond the Java/Spring stack, I work with AI-assisted development (GitHub Copilot, technical prompting) applied to refactoring, test generation and code review, along with quality practices: Clean Code, SOLID, code review and collaborative Git workflows (branching, pull requests, CI).

Analytical, hands-on and focused on continuous improvement, comfortable collaborating across technical and business teams within Agile/Scrum. Known for fast onboarding, technical autonomy and solving complex production incidents.

Tech stack

Languages

Java 8/11/17 (advanced), SQL, Go, Python

Frameworks

Spring Boot, Spring Batch, Spring Security, Spring Cloud, WebFlux

APIs & Auth

REST APIs, OpenAPI/Swagger, JWT, OAuth2, API security

Data

Oracle SQL, MySQL, SQL Server, MongoDB, Mongock, JPA/Hibernate

DevOps & CI

Docker, Git/GitHub, GitLab CI, Maven, Gradle

Architecture

Microservices, hexagonal, MVC, event-driven, high availability

Testing

JUnit 5, Mockito, Postman, Newman, integration and E2E

Quality

Clean Code, SOLID, refactoring, code review, Agile/Scrum

Applied AI

GitHub Copilot, technical prompting, AI-assisted tests and refactoring

Enterprise

IBM Mainframe/Host, banking, ABSIS architecture, legacy modernisation

Experience

Software Engineer · CaixaBank Tech

NOV 2024 — PRESENT

Barcelona · Hybrid

Backend microservices in a banking environment, on distributed architecture and business-critical high-availability systems.

REST APIs and batch processes with Java 8/11 and Spring Boot.
Development on ABSIS architecture with secure JWT authentication.
Integration and communication with IBM Mainframe / Host systems.
Design and tuning of complex SQL queries on Oracle.
Critical incident resolution and troubleshooting in TST/PRO.
Endpoint testing and integration with Postman and Newman.
Technical support and onboarding for new team members.
API and integration-flow documentation for business teams.
Agile/Scrum delivery with code reviews and quality standards.

Java 8/11Spring BootSpring CloudOracle SQLIBM HostDockerGitLab

Software Engineer · Reformastic

SEP 2024 — SEP 2025

Barcelona · Remote · Part-time

MVP 0 of a platform for the home-renovation sector, built on a microservices architecture.

Backend microservices with Java 11 and Spring Boot.
Design and implementation of REST APIs and business logic.
Data modelling and access with SQL and MongoDB.
Technical definition and refinement of user stories.
Architecture and scalability decisions for the MVP.

Java 11Spring BootMongoDBREST APIsDockerScrum

Backend Developer · Barcelona Activa · IT Academy

APR 2024 — NOV 2024

Barcelona · On-site

Collaborative microservices project with secure code execution inside isolated Docker containers.

Core engine for secure Java code execution in isolated containers.
JWT authentication with Spring Security and Mongock migrations.
REST APIs, automated testing and dual MongoDB/MySQL persistence.

JavaSpring SecurityMongoDBMySQLJUnitMockito

Technical Coordinator (Senior Technician) · Automatic Llobregat SL

MAY 2007 — JAN 2022

Barcelona · On-site

15 years in a technical and operational role: team coordination, projects and clients.

Coordination of a 5-person team and end-to-end project management.
Installation and maintenance of automation and home-automation systems.
Technical coordination with clients and suppliers; invoicing.

Team managementHome automationClient relations

Selected projects

ITA-Challenges Backend

OPEN SOURCE · IT ACADEMY

Open-source coding-challenge platform built as a team on a microservices architecture: challenge service, users with JWT authentication, scoring system and secure code execution in isolated Docker containers. Dual MongoDB/MySQL persistence with Mongock migrations, OpenAPI documentation and automated testing with JUnit and Mockito under Scrum with pull-request code review.

JavaSpring BootSpring SecurityMongoDBMySQLDockerGradleJWTJUnit

github.com/IT-Academy-BCN/ita-challenges-backend

Integra_Sequia

HACKATHON WINNER 2024

Winning project of the Barcelona Activa Hackathon 2024: an application around drought management in Barcelona, with a Java/Spring Boot backend, open-data integration and a working delivery in 48 hours with a cross-functional backend, frontend and data team.

JavaSpring BootREST APIOpen dataTeamwork

github.com/danidiazd

Education

Backend Java & Spring Boot Bootcamp

SEP 2023 — MAY 2024

IT Academy · Barcelona Activa

Java, Spring Boot, REST APIs, SQL, MongoDB, Docker, JUnit testing, microservices and agile methodologies.

Continuous certified training (250+ hours)

2023 — 2026

Udemy · IT Academy

Java Programming Master (128 h), Java Programming (38 h), Building an app from scratch in Go (28 h), MySQL databases (14 h), Git & GitHub (12 h), Clean Code and best practices (8 h), GitHub Copilot from zero to pro (8 h) and professional AI-assisted development.

Backend development · Self-taught

SEP 2022 — PRESENT

Ongoing

Advanced Spring Boot, reactive programming with WebFlux, microservices and system design.

Certifications

Certifications are listed on the certificates page. certificates page

Languages

Spanish

Native

Catalan

Bilingual (C1)

English

Technical (B1)

Winner · Barcelona Activa Hackathon 2024 · Barcelona