Senior Performance Test Engineer

Job description

We are looking for a Senior Performance Test Engineer to take ownership of performance testing within an international project.

In this role, you will drive the performance testing process end to end — from understanding business requirements and defining workload models through preparing test data and k6 scripts to test execution, results analysis and final recommendations.

We are looking for someone who does more than simply run performance tests. You should be able to understand what the results actually tell us — determine the practical performance ceiling of a system, identify potential bottlenecks and distinguish infrastructure issues from application errors, test-data problems or issues within the test scripts themselves.

You will work with k6, JavaScript, Azure DevOps, Prometheus and Grafana, collaborating across Development, DevOps, QA and business teams. You will also work closely with the Project Manager and Release Manager while taking ownership of the overall performance testing area.

IN SHORT:

• 100% REMOTELY or from one of our 2 offices
• 125 - 145 PLN/h + VAT

☑️ B2B contract

Your Daily Missions

• Owning performance testing end to end — from requirements and test-data preparation through execution, analysis and final reporting.
• Designing performance scenarios based on business requirements, including transactions per hour, load tiers and acceptance criteria.
• Building and maintaining performance test scripts using k6 and JavaScript.
• Selecting appropriate k6 workload models and executors for different performance scenarios.
• Testing REST API flows, including authentication, sessions and data correlation between individual steps.
• Preparing and validating test data, including CSV feeders and sensitive data.
• Running and parameterising performance tests through Azure DevOps Pipelines.
• Exporting and analysing performance metrics using Prometheus and Grafana.
• Correlating client-side test results with application and infrastructure metrics.
• Identifying bottlenecks, practical performance ceilings and the root causes of failures.
• Distinguishing between script, test-data, application, infrastructure and environment issues.
• Preparing clear performance reports and evidence-based recommendations for both technical and non-technical stakeholders.
• Identifying risks and blockers early and proposing appropriate mitigation.
• Coordinating performance-testing activities across Development, DevOps, QA and business teams and working closely with the Project Manager and Release Manager.
• Using AI tools to support script development, test-data preparation, log and result analysis and reporting while critically validating generated output.