Senior Data Developers (Python)

This opportunity is a consultancy mission delivered by Keystone Solutions for our client. The mission supports a major modernization program that transforms a legacy monolithic application into a modern microservices architecture running on Kubernetes. The program adopts an API-first and event-driven approach and progressively replaces the legacy platform. Beyond a technical upgrade, it is also a business transformation program: it enables the development of new features, improves agility, and accelerates the delivery of value to internal and external end users. By building a more flexible and scalable digital platform, the program supports better services, an enhanced user experience, and faster adaptation to constantly evolving business and regulatory needs.

As a Keystone Solutions consultant, you will work on site at the client (and in hybrid modes where applicable), embedded with their teams to deliver outcomes while benefiting from Keystone's community, frameworks, and coaching. You will represent Keystone Solutions' standards of excellence, contribute to knowledge sharing, and bring proven consulting practices to help the client achieve measurable results.

Role: Expert Application Developer (Most recent experience: any time). As the Expert Application Developer, you will carry out all responsibilities below under Keystone Solutions' consultancy model, working closely with the client's stakeholders and teams.

• →Contribute to the transformation of a legacy monolith into a modern microservices architecture operating on Kubernetes.
• →Apply an API-first and event-driven approach across services and integrations.
• →Support the broader business transformation by enabling new features, improving delivery agility, and accelerating value to internal and external users.
• →Help build a flexible, scalable digital platform that elevates service quality, enhances user experience, and adapts quickly to evolving business and regulatory needs.
• →Collaborate within Agile Scrum teams and contribute to DevOps practices, observability, and continuous improvement.

• API REST — Level: Expert; Most recent experience: any time
• Atlassian Suite — Level: Expert; Most recent experience: any time
• CI/CD — Level: Expert; Most recent experience: any time
• DB2 — Level: Expert; Most recent experience: any time
• DevOps — Level: Expert; Most recent experience: any time
• ELK tools — Level: Expert; Most recent experience: any time
• ETL — Level: Expert; Most recent experience: any time
• Framework Agile Scrum — Level: Expert; Most recent experience: any time
• GIT — Level: Expert; Most recent experience: any time
• IntelliJ — Level: Expert; Most recent experience: any time
• JSON — Level: Expert; Most recent experience: any time
• Kubernetes — Level: Expert; Most recent experience: any time
• Linux — Level: Expert; Most recent experience: any time
• Python — Level: Expert; Most recent experience: any time
• Spring Boot — Level: Expert; Most recent experience: any time
• SQL — Level: Expert; Most recent experience: any time
• UML — Level: Expert; Most recent experience: any time
• Visual Studio Code — Level: Expert; Most recent experience: any time

• English — Active knowledge
• Dutch or French — Nice to have

• Main address: Brussels

• Consultancy nature of work: Engage directly at client sites as a Keystone Solutions consultant, integrating with client teams while leveraging Keystone's proven delivery practices.
• Dynamic projects: Tackle diverse challenges across modernization, APIs, data platforms, and cloud-native engineering on different client missions.
• Turbo-charged learning and development: Access mentoring, certifications, knowledge-sharing sessions, and a strong engineering community to broaden your expertise.
• Ambition skyrocketing within a consultancy framework: Accelerate your career through varied engagements, visible impact, and a clear progression path supported by Keystone leadership.

Being a K‑Stone means living our values on every engagement: excellence in delivery, integrity in our commitments, curiosity in problem-solving, and teamwork that amplifies client impact. You will bring these values to the client's modernization program while upholding Keystone Solutions' consulting standards.

As an Expert Application Developer, you will apply your expertise in APIs, microservices on Kubernetes, DevOps, CI/CD, observability (ELK), data and integration (DB2, SQL, ETL), and modern engineering tooling (GIT, IntelliJ, Visual Studio Code) across multiple client scenarios. You will translate complex requirements into robust solutions, guide best practices in Agile Scrum environments, and coach peers to raise engineering quality throughout the client's platform.

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