Senior Java Developer with Apache Kafka (f/m/x)

Sii Poland; Warszawa; On-site; PLN 200,000 - 320,000; Full time

Benefits offered by this job

Great Place to Work

Centre of internal trainings

Profit sharing

Regular integration events and trips

Medical care

Job summary

Sii Poland in Warsaw is seeking an experienced Senior Java Developer to join a team building a modern data integration and processing platform supporting logistics on a global scale. You will design scalable backend services and microservices using Java and Spring Boot, with a focus on event-driven integrations via Apache Kafka.

The role requires hands-on production Kafka experience, architecture input, and collaboration with cross-functional teams to modernize legacy apps into cloud-ready

Qualifications

• Minimum 10 years of commercial software development experience.
• Strong senior-level Java backend expertise.
• Production experience with Apache Kafka.
• Experience designing microservices and event-driven architectures.
• Experience with distributed systems and enterprise integrations.
• Fluent English communication in international environments.
• Residence in Poland.
• CCDAK certification (Confluent Certified Developer for Apache Kafka).

Responsibilities

• Design, develop, and maintain scalable backend services and microservices with Java and Spring Boot.
• Implement event-driven data processing using Apache Kafka.
• Build enterprise integrations via APIs, messaging platforms, and asynchronous communication.
• Participate in technical design and architecture discussions.
• Modernize legacy applications into scalable, cloud-ready solutions.
• Monitor and optimize performance, reliability, and scalability across distributed environments.
• Collaborate with developers, architects, and stakeholders on data integration initiatives.

Skills

Java backend development

Event-driven architectures

Microservices design

Distributed systems

Kafka expertise

English communication

Architectural discussions

Tools

Apache Kafka

Kafka Streams

Kafka Connect

Kubernetes

OpenShift

Docker/Podman

Job description

We are looking for an experienced Senior Java Developer to join a team building a modern enterprise data integration and processing platform that supports key logistics and transportation processes on a global scale. This role focuses on developing scalable backend services, microservices, and event-driven integrations within a complex enterprise environment.

You will contribute to the design and implementation of solutions that enable efficient data processing and communication across business systems. An important part of the role involves modernizing legacy applications and delivering solutions aligned with Domain-Driven Design principles.

We are looking for a self-driven professional who can actively participate in architecture discussions and make sound technical decisions. Strong hands-on production experience with Apache Kafka is essential for success in this role.

Your tasks

• Designing, developing, and maintaining scalable backend services and microservices using Java and Spring Boot
• Implementing event-driven architectures and data-processing solutions based on Apache Kafka
• Building enterprise integrations between internal and external systems using APIs, messaging platforms, and asynchronous communication mechanisms
• Participating in technical design and solution architecture discussions, providing expertise in distributed systems and integration patterns
• Supporting the modernization and transformation of legacy applications into scalable, maintainable, and cloud-ready solutions
• Monitoring, troubleshooting, and optimizing application performance, reliability, and scalability across distributed environments
• Collaborating closely with developers, architects, and business stakeholders to deliver strategic data integration and digital transformation initiatives

Requirements

• Minimum 10 years of commercial software development experience, including strong senior-level expertise in Java backend development
• Strong hands-on production experience with Apache Kafka
• Proven experience designing and building microservices, scalable backend services, and event-driven architectures
• Practical experience working with distributed systems, enterprise integrations, and data processing solutions
• Ability to contribute independently to technical design and solution architecture discussions
• Very good English communication skills, enabling effective collaboration in an international environment
• Residence in Poland
• Valid Confluent Certified Developer for Apache Kafka (CCDAK) certification

Nice to have

• Production experience with Kafka Streams and Kafka Connect
• Experience with cloud-native and containerized environments, including Azure, Kubernetes, OpenShift, Docker, or Podman

Job no. JOB-DGAMP

Sii ensures that all hiring decisions are made solely on the basis of qualifications and competence. We are committed to equal and fair treatment of all, regardless of legally protected characteristics. At Sii, we promote a diverse and inclusive work environment, in full compliance with applicable anti-discrimination laws.

Benefits For You

• Great Place to Work
• Solid financial situation
• Contracts with the biggest brands
• Centre of internal trainings
• Many experts you can learn from
• Open and accessible management team
• Profit sharing
• Passion Sponsorship program
• Regular integration events and tripsComfortable and well-equipped offices
• MySii app
• Medical care