We’re looking for a QA Engineer to join a global technology and IT services organization supporting large-scale system modernization programs for enterprise clients.The team works on transforming complex, business-critical systems from legacy platforms into modern .NET and cloud-based solutions, with a strong focus on quality, stability, and data integrity.The role is part of a long-term modernization initiative involving backend systems, batch processing, integrations, and message-driven workflows. You’ll collaborate closely with developers, data engineers, and platform specialists to ensure that modernized applications behave consistently with legacy systems during parallel runs and cutover phases.Key responsibilities Design and execute manual and automated tests for .NET C# applications resulting from mainframe modernization Perform batch job and integration testing, including validation of long-running and scheduled processes Validate functional equivalence between legacy mainframe processes and modernized .NET/Azure solutions Test message-driven workflows and integrations using messaging systems (e.g. Azure Service Bus, IBM MQ) Execute regression, integration, and data consistency tests across interconnected systems Create and maintain automated tests using .NET test frameworks and integrate them into Azure DevOps CI/CD pipelines Analyze batch outputs, logs, audit trails, and data flows to ensure accuracy and completeness Collaborate with developers, data engineers, architects, and mainframe SMEs during parallel runs and cutover phases Ideal candidate profile Experience in QA / test automation for .NET C# backend systems Hands-on experience with batch processing and integration testing Knowledge of API testing (e.g. Postman / Newman) Experience working with Azure DevOps (pipelines, test plans, CI/CD) Good understanding of SQL and data validation in data-intensive systems Experience testing asynchronous or message-based systems Comfortable working in Agile and DevOps environments Nice to have Exposure to mainframe systems or modernization projects Experience with IBM MQ or Azure Service Bus Knowledge of batch orchestration and scheduling tools (e.g. Control-M, PowerShell) Background in industries with complex legacy systems (e.g. manufacturing, financial services, insurance) Conditions Work model: remote Salary: 150-210 pln/h Employment type: B2B Benefits: medical care, life insurance, trainings, Multisport card Recruitment steps Phone call with Recruiter (20 - 30 min.) Technical interview with Client (may required 2 rounds) Feedback and decision