Senior Java Software Developer

ALTEN; Brussel; Hybrid; EUR 90,000 - 130,000; Full time

Benefits offered by this job

Company car with fuel card

Group insurance & healthcare

Remote work possibility

Job summary

ALTEN in Belgium is hiring a Senior Java Software Developer to drive application modernization in Brussels. You will upgrade Java apps from legacy versions to modern runtimes, refactor code, and resolve migration challenges across teams.

The role requires deep Java expertise (7–21+), Spring, Tomcat and containerization with OpenShift/Kubernetes. Proficiency in English and Dutch or French is preferred, with a permanent contract and remote work options.

Qualifications

• At least 5 years of Java development experience, including Spring/Spring Boot.
• Strong Java expertise from Java 7 to Java 21+.
• Proven experience in large-scale Java upgrade and migration projects.
• Expert Java Core knowledge and enterprise app development.
• Troubleshooting across legacy architectures and complex issues.
• Experience with application servers and middleware technologies.
• Hands-on with Tomcat; OpenShift and Kubernetes are a strong asset.
• Good English; Dutch or French proficiency is a plus.

Responsibilities

• Analyze existing Java applications on legacy versions (starting from Java 7).
• Plan and execute migrations to modern Java versions (Java 17, 21+).
• Identify and resolve compatibility issues with frameworks, libraries, and servers.
• Refactor and modernize code per current Java best practices.
• Troubleshoot and resolve complex migration issues.
• Define migration strategies and roadmaps for legacy apps.
• Collaborate with development, architects, and infra teams during upgrades.
• Support testing, validation, and deployment of upgraded applications.
• Contribute to modernization of hosting environments, including containerization.

Skills

Java

Spring

Spring Boot

Java Versions 7-21

OpenShift

Kubernetes

Tomcat

CI/CD

Dutch or French

English

Tools

Tomcat

OpenShift

Kubernetes

Job description

The Position

As part of our ongoing growth, we are looking for a Senior Java Software Developer to join our teams and work on client projects located in Brussels. You will join our client’s application modernization initiative, focused on upgrading and modernizing a portfolio of existing Java applications running on legacy environments.

As a Senior Java Upgrade & Migration Engineer, your main responsibilities will include:

• Analyze existing Java applications running on legacy Java versions (starting from Java 7).


• Plan and execute migrations towards modern Java versions (Java 17, 21 and above).


• Identify and resolve compatibility issues related to frameworks, libraries, and application servers.


• Perform code refactoring and modernization to comply with current Java best practices.


• Troubleshoot and resolve complex technical issues during migration activities.


• Conduct impact assessments and define migration strategies for legacy applications.


• Collaborate with development teams, architects, and infrastructure experts throughout the upgrade process.


• Support testing, validation, and deployment of upgraded applications.


• Contribute to the modernization of application hosting environments.


• For part of the team, support containerization and deployment activities using OpenShift, Kubernetes, and Tomcat

Your profile

• You have at least 5 years of experience in Java, spring or spring boot


• You have strong experience in Java development with expertise ranging from Java 7 to Java 21+.


• You have proven experience in large-scale Java Upgrade & Migration projects.


• You have expert-level knowledge of Java Core and enterprise application development.


• You have strong analytical skills with extensive experience in troubleshooting and resolving complex technical issues.


• You are able to assess legacy architectures and define modernization roadmaps.


• You have experience with application servers and middleware technologies.


• You have hands-on experience with Tomcat.


• Experience with OpenShift, Kubernetes and containerized environments is considered a strong asset.


• Good understanding of CI/CD and modern deployment practices.


• Strong communication and collaboration skills.


• Professional proficiency in Dutch or French, combined with good English.

Working Conditions

• Permanent contract with an attractive salary package


• Company car with fuel card


• Group insurance & healthcare insurance


• Possibility of remote work


• 20 legal vacation days + 12 compensatory days

About ALTEN

ALTEN is a world leader in engineering and technology consulting, with over 57 000 employees in more than 30 countries. We support major companies in their innovation, R&D, and digital transformation projects across sectors such as automotive, aerospace, energy, finance, life sciences, and telecommunications.

Present in Belgium for over 25 years, ALTEN Belgium operates from its offices in Brussels and Antwerp. Today, with a team of 700 consultants ALTEN Belgium offers a wide range of expertise across Engineering, Life Sciences, and IT fields. From Automotive to Railway, and Medtech to Agrifood, our experts deploy their knowledge to provide innovative solutions in a dynamic and forward-thinking environment.

Ready for a new challenge?