# Back-end Developer

> COSMOTE GLOBAL SOLUTIONS NV · Brussels, Belgium · Contract · Posted 2026-05-08

**Workplace:** on_site

## Description

**COSMOTE Global Solutions NV**, a distinguished member of the OTE Group of Companies, is an ICT Systems Integrator offering a comprehensive range of ICT Solutions and Services. We are actively seeking a seasoned **Back-end Developer** to strengthen our innovative technology team.

In this role, you will be responsible for developing and maintaining robust server-side applications, ensuring seamless integration with front-end components, and optimizing system performance. You will collaborate with cross-functional teams to deliver scalable, secure, and efficient back-end solutions that meet business requirements.

**Key Responsibilities:**

-   Develop and maintain scalable back-end services and APIs.
-   Implement core business logic and ensure data integrity and security.
-   Integrate server-side logic with front-end components.
-   Design and optimize databases for performance and reliability.
-   Adopt secure coding practices to protect application and data security.
-   Follow best practices for code quality, versioning, and documentation.
-   Conduct code reviews, debugging, and testing to identify and resolve issues.
-   Collaborate with product managers, front-end developers, and other stakeholders during the development lifecycle.
-   Participate in architectural decisions and technology evaluations to improve system design.
-   Maintain up-to-date technical documentation.

## Requirements

-   Bachelor’s Degree in Computer Science, Engineering, or a related field.
-   Minimum of 13 years of professional experience in back-end development.
-   Strong proficiency in Java (version 17 or above), Kotlin, vert.x, Spring Boot (WebFlux), and Hibernate.
-   Experience with microservices architecture and API-driven development.
-   Knowledge of integration protocols such as AS4.
-   Proficient in database design and management using MongoDB, PostgreSQL, Virtuoso Triple Store, and OpenSearch.
-   Hands-on experience with containerization and orchestration tools such as Docker and Kubernetes.
-   Solid understanding of security frameworks including OpenID Connect, OAuth2, TLS, and Keycloak.
-   Experience with security testing and dependency management tools such as SAST, DAST, Fortify, SonarQube, Sonatype, Dependency-Track, and Maven.
-   Proficient with collaboration and productivity tools including JIRA, Confluence, Office 365, and SharePoint.
-   Excellent problem-solving skills, with the ability to work effectively in a multicultural and international environment.
-   Fluent in English (C2 level) both spoken and written.
-   Strong communication skills, adaptability, and capacity to work under changing requirements.

## Apply

[Apply at COSMOTE GLOBAL SOLUTIONS NV](https://apply.workable.com/cosmote-global-solutions-nv/j/9B21B5FE43/apply)

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