09/28/2026 updated
100 % available
Senior Java Backend Engineer | Spring Boot | Microservices | Cloud-Native
Barcelona, Spain
Worldwide
PhD, Software EngineeringAbout me
With 10+ years building and modernizing enterprise systems, specializing in Spring Boot, microservices architecture, and event-driven systems. Experience in migrating monolithic applications to cloud-native, container-based architectures. Hands-on expertise across the full CI/CD lifecycle
GitHub ActionsJava (Programming Language)GitHubPostgreSQLSoftware ArchitectureSoftware DesignEvent-driven ArchitectureMulti-Agent SystemsSpring BootGitLabBackend ProgrammingGitlab-ciApi DesignApi GatewayMicroservices
Java & Spring Boot Development
Expertise in building enterprise-grade backend systems using Java and Spring Boot, including Spring Security, Hibernate/JPA, and RESTful API design with over 10 years of hands-on experience.
Microservices & Event-Driven Architecture
Deep knowledge in designing and implementing microservices-based architectures with event-driven communication using Kafka, including service boundary definition, API Gateway integration, and fault-tolerant deployments with Resilience4j.
Cloud-Native & Container Technologies
Proficiency in containerizing and deploying applications using Docker and Kubernetes on AWS, with experience in CI/CD pipeline setup using Git, GitHub, GitLab, and Jenkins, as well as observability tooling such as Prometheus and Grafana.
Authentication & Security
Solid experience with authentication and authorization mechanisms including JWT, OAuth 2, and Keycloak-based identity management for securing microservices platforms.
Database Management
Hands-on experience with relational databases including PostgreSQL, MySQL, and MariaDB, as well as caching solutions using Redis for high-performance backend systems.
Testing Frameworks
Practical knowledge of unit and integration testing using JUnit, Mockito, and Spring Test to ensure software quality and reliability.
Frontend Technologies
Working knowledge of frontend technologies including React, Angular, TypeScript, JavaScript, HTML, CSS, and Bootstrap for full-stack development support.
AI & Multi-Agent Systems
Experience designing multi-agent AI architectures for SaaS platforms, orchestrating agent services via asynchronous Kafka messaging to automate HR workflows and personalized training recommendations.
Build & Dependency Management
Proficiency with build tools Maven and Gradle for managing Java project dependencies, builds, and lifecycle automation.
Agile & Project Management
Familiarity with Agile methodologies including Scrum and Kanban, supported by tooling such as Jira for project tracking and team collaboration.
Legacy System Modernization
Proven track record in assessing and modernizing legacy monolithic applications to cloud-native, microservices-based architectures while managing business risk during migration.
Expertise in building enterprise-grade backend systems using Java and Spring Boot, including Spring Security, Hibernate/JPA, and RESTful API design with over 10 years of hands-on experience.
Microservices & Event-Driven Architecture
Deep knowledge in designing and implementing microservices-based architectures with event-driven communication using Kafka, including service boundary definition, API Gateway integration, and fault-tolerant deployments with Resilience4j.
Cloud-Native & Container Technologies
Proficiency in containerizing and deploying applications using Docker and Kubernetes on AWS, with experience in CI/CD pipeline setup using Git, GitHub, GitLab, and Jenkins, as well as observability tooling such as Prometheus and Grafana.
Authentication & Security
Solid experience with authentication and authorization mechanisms including JWT, OAuth 2, and Keycloak-based identity management for securing microservices platforms.
Database Management
Hands-on experience with relational databases including PostgreSQL, MySQL, and MariaDB, as well as caching solutions using Redis for high-performance backend systems.
Testing Frameworks
Practical knowledge of unit and integration testing using JUnit, Mockito, and Spring Test to ensure software quality and reliability.
Frontend Technologies
Working knowledge of frontend technologies including React, Angular, TypeScript, JavaScript, HTML, CSS, and Bootstrap for full-stack development support.
AI & Multi-Agent Systems
Experience designing multi-agent AI architectures for SaaS platforms, orchestrating agent services via asynchronous Kafka messaging to automate HR workflows and personalized training recommendations.
Build & Dependency Management
Proficiency with build tools Maven and Gradle for managing Java project dependencies, builds, and lifecycle automation.
Agile & Project Management
Familiarity with Agile methodologies including Scrum and Kanban, supported by tooling such as Jira for project tracking and team collaboration.
Legacy System Modernization
Proven track record in assessing and modernizing legacy monolithic applications to cloud-native, microservices-based architectures while managing business risk during migration.
Experience
Professional experience5 - 10 years
Freelancer since2026
Languages
GermanGoodEnglishFluentFrenchFluentSpanishBasic knowledge
Project history
Applying for freelance software engineering and developing roles. Focused on continuous skill development in modern backend development, API design, CI/CD, cloud fundamentals, and AI agents integration to stay aligned with industry and emerging technologies.
Led the architectural migration of a legacy monolithic system to a microservices-based architecture, defining service boundaries and selecting the technology stack. Designed a multi-agent AI architecture for an HR SaaS platform and implemented core components orchestrating Planner, Research, Content, and Reviewer agent services via asynchronous Kafka messaging. Built the platform on Spring Boot microservices with an API Gateway, Keycloak-based authentication, Redis caching, and PostgreSQL persistence, deployed on Docker/Kubernetes in AWS with Resilience4j and Prometheus/Grafana. Conducted modernization assessments across existing applications, keeping select legacy modules in the monolith during migration to reduce business risk.
- Designed, developed, and maintained software applications for the digitalization and automation of administrative processes within public sector
- Developed and implemented business applications for registry office management, marriage management for family courts, and inventory management, replacing or reducing manual administrative procedures
- Participated in the modernization of legacy applications, migrating and progressively improving systems based on older technologies toward more maintainable and scalable architectures
- Worked extensively with Java/JEE, Hibernate, Spring Framework, and Struts in large-scale application development environments
- Designed and implemented 3-tier architectures, separating presentation, business logic, and data-access layers to improve maintainability and separation of concerns
- Developed communication mechanisms between application layers and services using HTTP-based interfaces, enabling interaction between frontend, backend/business services, and data-access components
- Designed and implemented REST-style services and backend business components to support the integration and reuse of application functionality
- Developed data-access and persistence components using Hibernate/JPA concepts, relational databases, and structured domain models
- Contributed to the transition from tightly coupled legacy applications toward more modular architectures, establishing a foundation for subsequent modernization and service-oriented approaches