Medior Full Stack Developer Consultant

Mission Overview

As part of a consultancy mission at a client site, Keystone Solutions is seeking talented consultants to enhance existing delivery teams involved in the development, integration, and evolution of critical public sector digital services. This role will focus on supporting the digital transformation of public administrations through the implementation of interoperable, secure, and scalable solutions that facilitate collaboration and information exchange between organizations. Key Activities

Development and maintenance of business-critical applications and shared services. Integration with internal and external systems through APIs and service-oriented architectures. Modernization, optimization, and continuous improvement of existing applications and technical platforms. Contribution to the implementation of secure and resilient digital services supporting public sector organizations. Languages

French or Dutch: Expert level English: Working proficiency Responsibilities

Development and maintenance of business applications and shared digital services. Development of application components, APIs, and web services. Contribute to the design of application architecture and technical building blocks in collaboration with technical leads and solution architects. Participate in technical workshops, Agile/Scrum ceremonies, and stakeholder meetings. Support testing activities, technical documentation, deployments, quality assurance, monitoring, reporting, and continuous improvement initiatives. Collaborate with multidisciplinary teams to ensure alignment with business and technical requirements. Ensure adherence to security, performance, interoperability, and quality standards. Experience

Minimum 5-7 years of professional experience in Java software development. Experience working in complex multi-system environments and large-scale digital transformation projects. Experience in public sector environments is considered an asset. Proven experience in Agile delivery environments. Competencies

Technical knowledge and practical experience of the following technologies:

Java >= 21 and Spring Framework (Core, JDBC, Data, Security, AOP) JPA / Hibernate RESTful Web Services OpenAPI / Swagger Keycloak, Lombok, MapStruct SOA, Backend-for-Frontend, CQRS Test-driven development (JUnit, Mockito, Spring Test, Cypress) Angular 20 Maven Docker OpenShift / Kubernetes Git and GitLab CI/CD SonarQube NPM OAuth 2.0 Flyway or Liquibase PostgreSQL, SQL Server and relational databases BPMN and UML Jira and Confluence Agile/Scrum methodologies Continuous Integration and Continuous Delivery (CI/CD)

Soft Skills

Strong analytical and problem-solving skills. Ability to quickly understand and maintain existing codebases. Customer and solution-oriented mindset. Team player with strong communication skills. Autonomous, proactive, and quality-focused. Mission & Working Conditions

This consultancy mission will be carried out within a hybrid working environment. Regular presence on site may be required depending on project needs and team activities. You will collaborate with multidisciplinary teams across different public sector organizations, providing a dynamic and enriching work experience. Duration

As soon as possible - 31/12/2026 4 months (full time) Skills required

Agile / Scrum

- Level: Confirmed - Most recent: Any time Angular 17

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French or Dutch: Expert level English: Working proficiency