Senior Java Performance Engineer

Quick Facts

• Role: Senior Java Performance Engineer

• Tech focus: Java 21, Spring Boot, distributed processing, and Azure SQL Hyperscale performance

• Work style: Hybrid (3 days/week in Kraków)

• Rate: up to 1,350 PLN/day

Description

You will build and modernize Java applications and microservices used for portfolio performance reporting in banking and financial services. The role emphasizes performance engineering across distributed processing (Apache Storm), database tuning (SQL Server / Azure SQL Hyperscale), production troubleshooting for nightly batch jobs, and cloud modernization/migration to Azure. You will also help strengthen application security by addressing open-source dependency vulnerabilities using SCA tools.

Responsibilities

• Develop and maintain Java 21 and Spring Boot batch applications and microservices, including major framework and dependency upgrades

• Operate, troubleshoot, and tune an Apache Storm-based processing cluster (worker balancing, restarts, alert configuration)

• Analyze and optimize SQL Server and Azure SQL Hyperscale workloads (execution plans, indexing, query tuning, and regression troubleshooting)

• Migrate mainframe batch jobs and DB2 data flows to Azure as part of a modernization initiative

• Monitor nightly batch performance against service-level targets; investigate production incidents and lead root cause analysis

• Address open-source dependency vulnerabilities using Nexus IQ (or similar SCA tools) with risk assessment and sign-off

• Collaborate with data, cloud, QA, application support, and external technology partners to deliver reliable, high-performing solutions

Requirements

• 18+ years of hands-on Java development experience (ideally in banking/financial services)

• Strong Java 17/21 and Spring Boot expertise, including experience with major upgrades (must-have)

• Proven SQL Server/Azure SQL performance tuning experience: execution plan analysis, query optimization, plan regression troubleshooting, CPU bottleneck resolution (must-have)

• Hands-on experience with distributed/stream processing technologies such as Apache Storm, Kafka Streams, or Apache Flink (must-have)

• Strong analytical and problem-solving skills with a proactive troubleshooting approach

• Strong communication skills with engineering teams, senior stakeholders, and external vendors

• Collaborative mindset working in globally distributed teams

Benefits

• Work on business-critical banking platforms and tackle complex performance challenges across Java, distributed processing, and Azure SQL

• Contribute to a major modernization program involving cloud technologies and legacy systems

• Collaborate with experienced international engineering teams and external technology partners

• Make a tangible impact on performance, stability, and security of enterprise applications