API Developer Java

Synechron Kraków 2026-10-22

For one of our Clients operating in the global financial services sector, we are seeking talented professionals to join long-term strategic initiatives.

In this role you’ll you’ll design, build, and run secure, scalable APIs that power our Client’s digital products and internal platorms. Working in a cross-functional engineering team, you’ll help deliver reliable services at pace—built with modern Java and cloud-native patterns, including event-driven architecture.


Ideal candidate should have:

  • Strong hands-on experience building APIs and backend services in Java (this is essential).
  • Solid experience with Spring Boot and build tooling such as Maven.
  • Strong understanding of backend architecture concepts (service design, data access, caching, resilience).
  • Strong knowledge of API architectural styles and integration patterns (REST; plus GraphQL/SOAP where applicable).
  • Experience with API tooling such as Postman, Swagger UI / OpenAPI, SoapUI.
  • Comfortable working with common data formats such as JSON and XML, XAML.
  • Proven ability to diagnose issues, fix defects, and improve performance and reliability.
  • Strong collaboration skills—able to work effectively across teams and communicate technical decisions clearly.

Nice to have:

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

ABOUT SYNECHRON

At Synechron, we believe in the power of digital to transform businesses for the better. Our global consulting firm combines creativity and innovative technology to deliver industry-leading digital solutions. Synechron’s progressive technologies and optimization strategies span end-to-end Artificial Intelligence, Consulting, Digital, Cloud & DevOps, Data, and Software Engineering, servicing an array of noteworthy financial services and technology firms. Through research and development initiatives in our Synechron Labs we develop solutions for modernization, from Artificial Intelligence and Blockchain to Data Science models, Digital Underwriting, mobile-first applications and more. Over the last 20+ years, our company has been honored with multiple employer awards, recognizing our commitment to our talented teams. With top clients to boast about, Synechron has a global workforce of 14,000+, and has 55 offices in 20 countries within key global markets. ,[ Build and evolve high-performing, scalable APIs and backend services using Java, Spring Boot, Maven (primarily developed in IntelliJ). , Collaborate with engineers, product owners, architects, and testers to deliver well-designed services aligned to business outcomes. , Design APIs using established standards and patterns (e.g., REST, and where relevant GraphQL/SOAP) with strong attention to versioning, backward compatibility, and consumer experience. , Integrate with third-party and internal APIs, ensuring resilience, observability, and clear error handling. , Develop and support event-driven services using KaXa (or similar), including topic design, schema evolution, and message reliability patterns. , Build cloud-ready services on AWS, including deployment and runtime considerations for: Kubernetes / EKS, Fargate, Redis, RDS, S3, Route 53 , Own quality: write automated tests, perform regular API testing, and troubleshoot production issues with a “you build it, you run it” mindset. , Produce and maintain clear API documentation for internal and external consumers (OpenAPI/Swagger), plus runbooks where needed. , Contribute to engineering standards: security-by-design, performance, maintainability, and continuous improvement.] Requirements: Java, API, Spring Boot, Maven, REST API, GraphQL, SOAP, Postman, Swagger, OpenAPI, JSON, XML, AWS, Kubernetes, Redis, RDS, CI/CD