Java Developer

Quick Facts

• Role: Java Developer
• Work mode: Hybrid (2–3 days/week in Gdańsk office)
• Compensation (B2B): 750–860 PLN/month

Description

Develop and maintain backend systems supporting retail sales, including a central coupons, vouchers, and benefits service and an integration layer connecting sales and warehouse systems with an external RFID product registry. Build a Java library to work with RFID readers and deliver reliable, fault-tolerant communication that can keep the system running in offline mode when external systems are unavailable. The project operates at high scale and supports day-to-day sales and warehouse processes.

Responsibilities

• Develop sales support systems
• Build and maintain the central coupons, vouchers, and benefits service
• Develop an integration adapter between sales/warehouse systems and an external RFID registry
• Develop a Java library for RFID reader handling
• Create and maintain reliable communication between systems
• Implement resilience mechanisms for external system outages
• Enable offline operation for the systems

Requirements

• Very good knowledge of Java 25 (must have) and knowledge of Java 8
• Experience with Spring Boot 3.4–3.5 including Web, Security + JWT, Data JPA, Spring JDBC, AOP, Actuator, and Validation
• Knowledge of Spring WebFlux WebClient and Resilience4j (circuit breaker)
• Experience with JDBI 3, Liquibase, and Lombok
• Knowledge of springdoc OpenAPI, Micrometer, Prometheus, and OpenTelemetry/OTLP
• Experience with jSerialComm for serial communication and RFID readers
• Knowledge of Swing, Apache POI, and OpenPDF
• Experience with PostgreSQL, SQLite, and H2
• Knowledge of caching solutions like Redis or Dragonfly
• Testing experience with JUnit 5, Mockito, Spring Test, Testcontainers, and ArchUnit
• Knowledge of SonarQube and JaCoCo
• Experience with Gradle 7.6–9, Docker, Artifactory, GitLab CI, Jenkins, ArgoCD, and OpenShift

Benefits

• Work on high-scale, mission-critical solutions used in daily sales and warehouse operations
• Use modern stack based on Java 25 and Spring Boot 3.5
• Gain experience with hardware integration, RFID communication, and offline/fault-tolerant system design