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# Java Developer ID80054

- **Company:** Número De
- **Location:** Madrid, Spain
- **Contract:** Permanent contract
- **Skills:** Java (Programming Language), Application Programming Interfaces (APIs), Automation of Tests, Unit Testing, Program Optimization, Software Quality, Data Architecture, Software Design Patterns, Memory Management, Junit, PostgreSQL, MongoDB, NoSQL, Performance Tuning, Software Architecture, Mockito, Test-Driven Development (TDD), Spring-boot, Backend, Front End Software Development, Restful APIs, Microservices
- **Published:** July 28, 2026
- **Apply:** https://www.adzuna.es/contact-us.html

## About the Role

If you're looking for a place to grow, make an impact, and work with people who care, we'd love to meet you!, 4+ years of professional backend software development experience;

 - Expert-level knowledge of Java 11+ and deep familiarity with the Spring/Spring Boot ecosystem;
 - Broad knowledge of backend architecture, Microservices, and RESTful APIs;
 - Superior analytical and problem-solving ability;
 - Experience with automated unit testing and test-driven development using JUnit and Mockito;
 - Robust understanding of performance issues, computational complexity, memory management, and code optimization;
 - Familiarity with industry-standard algorithms, design patterns, and PostgreSQL, MongoDB, or other relational/NoSQL databases;
 - Effective communication skills to work with different teams across an international company;
 - Upper-intermediate English level.

## Description

We are looking for a Senior Java Developer to design, build, and maintain highly scalable and secure backend services and APIs for an international engineering team. You will work across Java 11+ and Spring Boot in a microservices architecture, optimize PostgreSQL and MongoDB database schemas, implement automated testing with JUnit and Mockito, and collaborate closely with frontend, product, and QA teams to deliver production-ready features. The role requires expert-level Java knowledge with strong performance optimization and code quality standards.
WHAT YOU WILL DO

 - Design, build, and maintain highly scalable, secure, and reliable backend services and APIs;
 - Translate application storyboards and use cases into functional, production-ready applications;
 - Identify bottlenecks and bugs, and devise solutions to mitigate and address these issues;
 - Collaborate closely with frontend developers, product managers, and QA to deliver end-to-end features;
 - Participate in peer code reviews to ensure code quality and adherence to best practices;
 - Maintain and optimize database schemas, queries, and overall data architecture.


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