Lead Java Backend Engineer

Project overview

This is a hands-on technical lead role building and modernizing Java and Kotlin Spring Boot services for order and trade lifecycle processing, including REST APIs and event-driven flows. The core requirements include Java 8–21 and migration experience, Spring Boot, Kafka and Kafka Streams, PostgreSQL, Docker, Kubernetes, GCP, CI/CD, automated testing, secure development, and L3 production support for low-latency, high-throughput services.

The lead will guide engineers while contributing to design, implementation, code reviews, troubleshooting, and Agile delivery; hands-on GenAI-assisted development with Claude Code and Claude Certified Architect – Foundations are also specified. The stated experience range is 8–10 years, consistent with the description’s minimum of 8 years, including technical leadership in a large-scale or complex environment. The role is a contract position in Krakow; work mode is not specified, and although trading-platform exposure is a nice-to-have, the description does not establish a specific employer industry.

Responsibilities

• Provide hands‑on technical leadership to the crew, guiding engineers on design, implementation, and engineering standards, and mentoring team members to grow their skills.
• Design, build, and enhance Java (8–21) and Kotlin Spring Boot microservices and REST APIs across the order and trade lifecycle, including order capture, validation, routing, execution, allocation, and booking.
• Build event‑driven flows using Kafka and Kafka Streams to deliver reliable, real‑time order and trade processing.
• Deliver containerized services with Docker and Kubernetes on GCP, and manage data on PostgreSQL.
• Apply engineering best practices, including clean code, CI/CD, secure SDLC, and automated testing with JUnit and Mockito.
• Own L3 production support, including performance profiling, incident resolution, and root cause analysis, keeping low‑latency, high‑throughput trading services resilient and stable.
• Use GenAI‑assisted development, including Claude Code, to improve engineering productivity and code quality across the team.
• Collaborate closely with Product Owners, Architects, and engineers, and lead code reviews, testing strategies, and troubleshooting of complex technical issues.
• Drive modernization efforts by evolving legacy systems toward modular, cloud‑native, and event‑driven architectures on GCP.
• Strong hands‑on experience in Java 8, 11, 17, and 21, including migrating applications across Java versions, building scalable microservices with Spring Boot, and designing REST APIs; experience with Kotlin.
• Experience with event‑driven architectures using Kafka and Kafka Streams, and with relational data stores such as PostgreSQL.
• Experience delivering containerized services with Docker and Kubernetes on GCP through CI/CD pipelines with automated testing, applying performance optimization, reliability, and secure development practices to low‑latency, high‑throughput services.

Requirements

• 8+ years of hands-on Java software engineering in large-scale or complex environments
• Java 8, 11, 17, and 21, including application migration across Java versions
• Spring Boot microservices and REST API design
• Kotlin experience
• Event-driven architecture with Kafka and Kafka Streams
• Relational data stores, including PostgreSQL
• Docker and Kubernetes
• GCP cloud delivery
• CI/CD pipelines and automated testing
• JUnit and Mockito
• Performance optimization and reliability for low-latency, high-throughput services
• L3 production support, performance profiling, incident resolution, and root cause analysis
• Secure development practices and secure SDLC
• Hands-on GenAI-assisted development, including Claude Code
• Claude Certified Architect – Foundations certification
• Hands-on technical leadership, mentoring, and engineering guidance
• Agile delivery and collaboration across engineering, product, and architecture

Project details

• Start: flexible
• Remote: hybrid
• Location: Poland, PL