Senior Fullstack Java Developer

Mission Overview:

Keystone Solutions is seeking a Senior Fullstack Java Developer for a consultancy mission at a client site. The organization operates in a complex technological environment, combining a historical application landscape with modern components. This role involves participating in a structural transformation of the IT landscape, modernizing architectures, reducing technical debt, adopting Cloud solutions, and ensuring compliance with regulations, including NIS2.

The existing applications cover critical areas such as unemployment regulation, payments, debt management, and financial and accounting processing. Some of these systems rely on legacy technologies, while new Cloud/hybrid architectures are emerging. The architect plays a key role in harmonizing, securing, and aligning these architectures.

Main Responsibilities:

As a consultant representing Keystone Solutions, you will carry out the following responsibilities:

• As a Programmer: Develop and/or adapt IT applications to provide efficient and user-friendly tools for end-users.
• As an Analyst-Programmer: Analyze the technical specifications of an application to choose the best solution and execute this analysis (for smaller projects) to enable users to perform their tasks efficiently and ensure the optimal and controlled functioning of IT resources.
• As a Specialist:
  • Conduct technical analyses within business projects.
  • Advise on integrations, data models, performance, and scalability.
  • Support the team in adopting technologies and architectural patterns.
  • Analyze and resolve complex technical issues in a highly interconnected environment.
  • Ensure coherence between legacy and modern components.

Technical Skills Required:

• Proven experience (5-7+ years) in complex IT programming.
• Expertise in modern Java (Spring, microservices, API-driven, event-driven).
• Skills in containerization and orchestrators (OpenShift).
• Advanced knowledge of relational databases (MySQL) and data modeling.
• Knowledge of integrations: messaging, REST/GraphQL, event-driven.
• Understanding of resilient architectures and high availability.
• Familiarity with security standards (NIS2).

Behavioral Skills:

• Excellent analytical and synthesis skills.
• Structured and pedagogical communication.
• Global vision and ability to maintain an overview.
• Quality orientation, autonomy, and proactivity.
• Ability to connect business needs with technical challenges.

Education:

Master's degree in Computer Science or equivalent experience.

Language Skills:

Very good command of French, Dutch, and English.

Working Conditions:

Remote work is possible (2 days per week) after 2 weeks of on-site presence.

If you are ready to tackle technical and strategic challenges in a dynamic consultancy environment, apply today at Keystone Solutions Career Portal.

Duration: 01/10/2026 - 31/12/2026 3 months • (full time)

Skills required:

• Agile / Scrum level expert - Level: Confirmed - Most recent: Any time
• Altassian Stack level confirmed - Level: Confirmed - Most recent: Any time
• Angular / ReactJS - Level: Confirmed - Most recent: Any time
• Docker/ JSF/ SonarQube/SOAP/Swagger/ OpenAPI/ Openshift Level Confirmed - Level: Confirmed - Most recent: Any time
• Expérience au sein d’un service public fédéral - Level: Confirmed - Most recent: Any time
• Hexagonal Architecture Level Confirmed - Level: Confirmed - Most recent: Any time
• IntelliJ Level Expert - Level: Confirmed - Most recent: Any time
• Java Level Expert - Level: Confirmed - Most recent: Any time
• Jira / Confluence - Level: Confirmed - Most recent: Any time
• JUnit/ SQL / Flyway Level Expert - Level: Confirmed - Most recent: Any time
• Lombok Level Confirmed - Level: Confirmed - Most recent: Any time
• Maven/Git/Rest Level Expert - Level: Confirmed - Most recent: Any time
• NPM/ IBM websphere Level Confirmed - Level: Confirmed - Most recent: Any time
• Spring/ spring boot Level Expert - Level: Confirmed - Most recent: Any time

Language requirements:

Dutch
Level Active knowledge
English
Level Active knowledge
French
Level Active knowledge