Senior Backend Engineer Java

What you will do

You will be responsible for designing, developing, and evolving the backend foundations of a next-generation digital platform for a Belgian public-sector organisation. Working closely with the Digital Platform Architect, you will contribute to building scalable, secure, and maintainable APIs, integration services, and Backend-for-Frontend (BFF) capabilities.

Your primary responsibilities include:

• Design, develop, and maintain platform APIs, backend services, and integration components
• Build scalable and maintainable backend services supporting multiple digital channels
• Contribute to the evolution of the platform integration layer
• Develop reusable backend capabilities for business domains and partner integrations
• Ensure consistency, reliability, and quality across platform services and APIs
• Implement integration patterns in line with platform architecture
• Contribute to API lifecycle management and versioning strategies
• Ensure services are secure, scalable, and resilient
• Apply software engineering best practices and coding standards
• Participate in code reviews, technical discussions, and architecture design
• Implement automated testing strategies and quality controls

You will also support troubleshooting and root cause analysis, collaborate with mobile engineers, participate in proof-of-concepts and MVP development, and contribute to performance and maintainability improvements.

What we are looking for

Technical experience:

• Proven experience as a Backend Engineer, Software Engineer, API Engineer, or similar
• Strong experience delivering production-grade APIs and backend services
• Expertise in REST APIs and API lifecycle management
• Experience with integration patterns and system-to-system integrations
• Understanding of Backend-for-Frontend (BFF) architectures
• Knowledge of API-first and service-oriented architectures
• Experience with authentication and authorisation (OAuth2, OpenID Connect, JWT)
• Understanding of cloud-based and distributed architectures
• Experience with automated testing and quality practices
• Knowledge of monitoring, observability, and operational practices
• Experience working in Agile environments

Profile:

• Strong analytical and problem-solving skills
• Ability to work independently and collaboratively
• Excellent communication and teamwork skills
• Confidence to challenge technical decisions constructively
• Pragmatic and delivery-oriented mindset
• Strong learning mindset and adaptability
• Ability to balance technical quality with delivery timelines

Languages:

• French or Dutch (at least one is mandatory)
• English (mandatory)

The setting

This is a full-time consultancy assignment at a Belgian public-sector organisation in Brussels. You will play a key role in establishing the integration layer between digital channels, enterprise systems, and partner ecosystems, while actively contributing to architecture implementation and platform delivery.

You can join us for this assignment as a freelancer or as an employee of HumanInTech. Same role, same team. If you join as an employee, your employment continues beyond this assignment. When it ends, we’ll work together to find your next assignment.

Location: Brussels

Employer / contracting party: HumanInTech

Engagement: Freelance or employed by HumanInTech

Working hours: Full-time

Experience: 6–10 years or more

Education: Bachelor's or more

Published: September 2026