Senior Backend Developer (Java)

Quick Facts

• Role: Senior Backend Developer (Java)

• Location/Work style: Warsaw, 4 days per month from Warsaw

• Employment: Full-time, B2B contract (12 months + extensions)

• Start date: 01.10.2026

Description

You will create and develop backend applications in Java and handle large volumes of database queries and text-file processing. You will manage and configure messaging systems using Kafka and Kafka Streams, implement design patterns, and collaborate with the team on system design. You will also maintain and improve CI/CD systems.

Responsibilities

• Develop and improve Java backend applications

• Process large volumes of queries and text files using databases

• Configure and manage Kafka and Kafka Streams-based queue/messaging systems

• Implement design patterns in application code

• Work closely with the team on system architecture and design

• Maintain and evolve CI/CD systems

Requirements (Must Haves)

• Java 21/25 with at least 6 years of experience

• PostgreSQL and Elasticsearch with at least 4 years of experience

• Kafka and Kafka Streams with at least 3 years of experience

• Strong knowledge of design patterns

• Knowledge of Enterprise Architect and UML

• Experience with application servers: Tomcat and Netty

• Spring Boot 2.3/2.4/2.6 with at least 4 years of experience

• Experience with monitoring tools: Prometheus/Grafana/Sentry/Loki

Benefits

• B2B contract for 12 months with potential extensions

• Opportunity to work on enterprise-scale backend systems in a banking environment