Senior Java Developer (86/989)

SUMMARY

💰 130 - 150 PLN/h on B2B

💰 15 600 - 18 000 PLN gross on UoP

📍 Kraków (Hybrid - 3 days in the office / 2 days remote)

💼 Senior

PROJECT

Join an engineering team responsible for developing core backend services for a modern, cloud-native platform.

As a Senior Java Backend Developer, you will build scalable and reliable services using Java, Spring Boot, and Apache Kafka, with a strong focus on event-driven architecture, asynchronous processing, APIs, and enterprise integrations. You will work on business-critical services and ensure they are maintainable, resilient, observable, and ready for production environments.

YOU WILL

• Design and develop modular backend services using Java and Spring Boot
• Build event-driven and asynchronous solutions based on Apache Kafka
• Implement resilient messaging patterns such as outbox, idempotent consumers, retries, and dead-letter queues
• Design and develop REST APIs following agreed API standards and contract-first practices
• Implement business logic, workflow automation, and rule-driven processing
• Integrate services with internal and external systems using REST, messaging, Kafka Connect, CDC, and other integration patterns
• Contribute to event and schema governance using Avro, JSON Schema, Schema Registry, or similar technologies
• Work with relational databases using SQL, JPA/Hibernate, and transactional processing
• Improve performance, reliability, and scalability of backend services and event flows
• Support distributed tracing, monitoring, and troubleshooting across distributed systems
• Collaborate with architects, QA, and platform teams to deliver production-ready solutions

MUST HAVE

• Strong commercial experience with Java, preferably Java 17+
• Very good knowledge of Spring Boot
• Hands-on experience with Apache Kafka and event-driven systems
• Good understanding of event-driven architecture and asynchronous processing
• Knowledge of messaging patterns such as retries, idempotency, dead-letter queues, and delivery guarantees
• Experience designing and implementing REST APIs, ideally using OpenAPI
• Good understanding of distributed systems concepts, including ordering, eventual consistency, and failure handling
• Strong experience with relational databases and SQL
• Practical knowledge of JPA/Hibernate, transactions, and database performance optimisation
• Strong understanding of OOP, clean architecture, and maintainable software design
• Experience troubleshooting performance and reliability issues in distributed or asynchronous systems
• Ability to translate business requirements into reliable backend solutions
• English allowing effective communication in an international engineering environment

NICE TO HAVE

• Experience with Kafka Connect, Debezium, and/or Change Data Capture (CDC)
• Experience with Avro, Schema Registry, or event schema governance
• Knowledge of CQRS, Saga, and/or Event Sourcing patterns
• Experience with workflow or rules engines such as Camunda or Drools
• Familiarity with caching and enterprise integration patterns
• Experience with observability, distributed tracing, and monitoring of backend services
• Experience with cloud-native environments, particularly AWS or other public cloud platforms
• Experience integrating applications with AI models or AI platforms

OUR OFFER

• The relocation package (4500 PLN total value) is paid in three installments (1500 PLN per month) if your permanent office presence is mandatory and you need to relocate from another city.
• Benefits: Extended medical care (over 2000 medical facilities in Poland, 80 in Kraków) for you and your family; Multisport card; Life insurance