API Developer

Your tasks

• 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 Kafka (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

• 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.

Must have: Java, API, Spring Boot, Maven, Postman, Swagger, SoapUI, JSON, XML

Nice to have: Kafka, AWS, Kubernetes, Redis

What we offer

• Prestigious position at one of the world’s largest banks.
• Stable, long-term projects.
• Competitive salary with a B2B contract.
• Hybrid work (6 days per month from the office in Cracow).
• Private healthcare and multisport card.
• Personal growth and development opportunities with the possibility to rotate between projects.