Senior API Developer – Java and Cloud-Native Architecture

Empower the Future of Digital Banking — Lead the Development of Cutting-Edge APIs in a Cloud-Native Ecosystem!

Krakow-based opportunity with hybrid work model (up to 3 days remote per week).

As a Senior API Developer – Java and Cloud-Native Architecture, you will be working for our client, a leading financial institution committed to innovative, secure, and scalable digital solutions. You will help design, build, and operate resilient APIs that fuel HSBC’s digital products and internal platforms, shaping the future of banking technology with modern Java and cloud-native patterns. This role offers a unique chance to work on impactful projects that define the banking experience of tomorrow while growing your engineering expertise in a dynamic environment.

Your main responsibilities:

• Build and evolve high-performing, scalable APIs and backend services using Java, Spring Boot, Maven, primarily within IntelliJ.
• Collaborate effectively with cross-functional teams—including engineers, product owners, architects, and testers—to deliver reliable services aligned with business objectives.
• Design APIs following established standards (REST, GraphQL, SOAP) with attention to versioning, backward compatibility, and user experience.
• Integrate with third-party and internal APIs, ensuring system resilience, observability, and robust error handling.
• Develop and support event-driven services using Kafka, including schema evolution, topic design, and message reliability patterns.
• Build cloud-ready services on AWS, considering deployment and runtime aspects for Kubernetes/EKS, Fargate, Redis, RDS, S3, and Route 53.
• Own quality assurance by writing automated tests, conducting API testing, and troubleshooting production issues, embracing a “you build it, you run it” mindset.
• Produce and maintain clear API documentation (OpenAPI/Swagger) and operational runbooks where needed.
• Contribute to engineering standards emphasizing security-by-design, performance, and maintainability, driving continuous improvement.

You're ideal for this role if you have:

• 5+ years of experience building APIs and backend services in Java.
• Strong expertise with Spring Boot and build tools like Maven.
• Deep understanding of backend architecture concepts such as service design, data access, caching, and resilience.
• Proven experience with API architectural styles (REST, GraphQL, SOAP) and integration patterns.
• Hands-on experience with API tooling (Postman, Swagger UI/OpenAPI, SoapUI).
• Proficiency working with data formats like JSON, XML, XAML.
• A track record of diagnosing issues, fixing defects, and enhancing system performance and reliability.
• Excellent collaboration skills and the ability to communicate complex technical ideas clearly.

It is a strong plus if you have:

• Experience with event-driven architecture at scale (Kafka streams, schema registry, idempotency, exactly-once/at-least-once patterns).
• Background building and operating services on AWS (Kubernetes/EKS, Fargate, Redis, RDS, S3, Route 53).
• Familiarity with CI/CD pipelines, observability tools (logging, metrics, tracing), and secure coding practices.
• Strong critical thinking with a pragmatic, delivery-focused mindset.

Language Required for the role:

• Fluent English command (spoken and written).

Eligibility for the role:

• Only candidates with an existing legal right to work in the European Union will be considered for this role.

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Interested? Apply now and include your CV (preferably in English) along with a statement confirming your consent to the processing and storage of your personal data.