Senior Java Backend Engineer (Freelance)

About the role

We are seeking a Senior Java Backend Engineer on a freelance basis to help design, develop, and evolve a next‑generation digital platform. You will work on scalable backend services, APIs, and integration components that support multiple digital channels and enterprise systems.

Key responsibilities

• Design, develop, and maintain robust backend services, REST APIs and integration layers.
• Build reusable capabilities for business domains and partner integrations.
• Implement integration patterns aligned with the platform architecture and ensure API lifecycle management.
• Apply best‑practice software engineering standards, automated testing and code reviews.
• Support troubleshooting, root‑cause analysis and continuous improvement initiatives.
• Participate in proof‑of‑concepts, MVPs and technical validation activities.
• Collaborate with architects, developers and other technical stakeholders to improve performance, reliability and maintainability.

Required profile

• Minimum 5 years of experience as a backend, software or API engineer.
• Delivery‑oriented mindset with strong analytical and problem‑solving skills.
• Ability to work independently as well as collaboratively in a remote or distributed setting.
• Excellent communication skills and a proactive attitude toward technical decisions.

Required skills

• Java development (minimum 5 years).
• Spring Framework.
• Design and implementation of production‑grade REST APIs.
• API lifecycle management and versioning.
• Backend‑for‑Frontend (BFF) architectures.
• Integration patterns and system‑to‑system integrations.
• API‑first and service‑oriented architecture principles.
• OAuth2, OpenID Connect and JWT for authentication/authorization.
• IBM MQ / MQ Series and IBM environment knowledge.
• Web services, object‑oriented programming principles.
• Software testing, quality‑assurance practices.
• Jira for development collaboration.
• Monitoring, observability and operational best practices.