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April 8, 2026

Senior Java Developer

Senior • Remote

120 - 135 PLN

Warsaw, Poland

Senior Backend Engineer (Java/Kotlin)

We are looking for an experienced Backend Engineer to join a team building modern, scalable systems based on a microservices architecture. This role offers real influence over technical decisions, system architecture, and the quality of delivered solutions—particularly within payment and subscription platforms.

Responsibilities

  • Design, develop, and maintain backend systems using Java or Kotlin and the Spring Framework

  • Build and evolve microservices following DDD, CQRS, and Hexagonal Architecture principles

  • Implement event-driven communication, ideally using Apache Kafka

  • Work with relational databases (PostgreSQL or other SQL databases) and optimize queries

  • Write unit and integration tests using JUnit, Mockito, and Testcontainers

  • Contribute to the design and development of cloud-based solutions (AWS or GCP)

  • Participate in code reviews and drive high engineering standards

  • Collaborate closely with product and engineering teams to deliver business-critical features

Requirements

  • Strong experience with Java and/or Kotlin

  • Solid knowledge of Spring / Spring Boot

  • Hands-on experience with SQL and relational databases (preferably PostgreSQL)

  • Proven background in microservices-based architectures

  • Experience with event-driven systems (Kafka is a strong plus)

  • Practical experience with backend testing (JUnit, Mockito, Testcontainers)

  • Experience working with cloud platforms (AWS or GCP)

  • Good understanding of Domain-Driven Design (DDD), CQRS, and Hexagonal Architecture

  • Must-have: experience with payment systems and/or subscription-based platforms

Nice to Have

  • Experience working with high-scale, high-availability systems

  • Knowledge of security and transactional data handling

  • Background in product-driven, Agile environments