Senior Legacy Migration Engineer

About the Company At Avaron, you get the security of permanent employment combined with the variety of working at different customers. We place specialists across everything from tech, IT and industry to project management and business support – and whatever the assignment, you have a consultant manager who is there for you and your development. About the Role You will take end-to-end technical ownership of migration and stabilization work for business-critical integrations in an insurance and pension platform. The environment combines legacy services and modern components, where safe cutovers, stable operations and clear rollback plans are essential. You will work independently in complex legacy environments while collaborating closely with infrastructure, DBA, MQ and operations teams. This is a strong opportunity if you enjoy solving difficult migration challenges in regulated systems where your technical decisions have immediate business impact. Job DescriptionYou will execute migration work across legacy and modern integration components. You will validate environment parity and remove runtime blockers ahead of cutover. You will diagnose and resolve production-critical issues in services, queues and integrations. You will build and run end-to-end verification and rollback tests. You will create concise runbooks and deployment notes to support repeatable execution. You will secure acceptance criteria before go or no-go decisions and help minimize business disruption during releases. RequirementsStrong experience with C# and .NET Framework 4.x. Experience maintaining and migrating WCF, SOAP and ASMX services. Hands-on experience with IIS deployment and troubleshooting, including application pools, bindings and configuration. Experience with Windows Services and Task Scheduler based batch operations. Ability to troubleshoot SQL Server issues and handle secure configuration. Knowledge of IBM MQ integration fundamentals, including connectivity and queue or channel diagnostics. Experience using PowerShell for deployment, verification and operational tasks. Experience working with TFS and Git based workflows and collaborating around CI/CD pipelines. General knowledge of PKI. You have delivered migrations in legacy enterprise systems with low incident impact. You have direct production experience from IIS together with WCF or ASMX cutovers. You can plan and execute rollback activities in real release situations. Nice to have Experience in at least two of the following areas is a plus: C or C++ maintenance in Windows service environments. Mainframe-adjacent integration patterns such as EBCDIC and file bridge patterns. Container and Kubernetes exposure for coexistence with modern APIs. Production observability and incident response in regulated environments. Legacy security hardening, including service accounts and encrypted settings portability. Exposure to .NET Framework 3.5. What We OfferPermanent employment at Avaron AB Occupational pension Wellness allowance of SEK 5,000 per year Application Selections are made on an ongoing basis – apply as soon as you can.