Senior .NET Engineer

We are seeking an experienced Senior .NET Engineer to join a high\-impact, strategic technology initiative. Our mission is to evolve a core business application for a market\-leading enterprise, proactively transforming the platform into a secure, maintainable, and high\-performance architecture. As a key specialist on the backend team, you will apply your deep .NET expertise to execute the complex migration from .NET Framework to .NET 10, ensuring the new architecture is robust, efficient, and built for scale. What You'll Do: * Execute the hands\-on migration of all backend projects from .NET Framework 4\.5\.2 to the .NET 10 target framework. * Play a critical role in refactoring the application's core architecture, replacing the legacy OWIN\-based pipeline with modern ASP.NET Core middleware. * Systematically refactor all code to remove dependencies on System.Web, implementing modern equivalents for HttpContext, Session state, and other legacy components. * Identify, analyze, and replace all incompatible and deprecated NuGet packages (e.g., Microsoft.Owin, Swashbuckle.Core) with modern, supported equivalents. * Update the data access layer to be compatible with the modernized stack, including migrating from MySql.Data.Entity to MySql.EntityFrameworkCore or a similar modern driver. * Collaborate with the Lead Engineer and DevOps team to integrate the modernized backend into new YAML\-based CI/CD pipelines in Azure DevOps. * Partner with the QA team to test and validate the refactored components, ensuring functionality and performance meet project benchmarks. What We're Looking For: * Significant experience as a Senior .NET Engineer, with a proven history of working on complex, large\-scale backend systems. * **Expert\-level knowledge of the .NET Framework 4\.x** , including ASP.NET, System.Web, and the OWIN pipeline. (You must understand the legacy to replace it.) * **Expert\-level knowledge of modern .NET 10** , including ASP.NET Core middleware, dependency injection, and the Kestrel web server. * Demonstrable experience having successfully completed a .NET Framework to .NET Core migration is highly desirable. * Strong experience with data access layers and ORMs (like Entity Framework), with specific experience with MySQL being a major plus. * Familiarity with Azure DevOps and YAML\-based CI/CD pipelines. * Excellent problem\-solving skills and the ability to dissect and refactor complex, legacy codebases. * Exceptional command of written and spoken English. Why Join Us? * Tackle one of the most challenging and rewarding tasks in backend engineering: a full\-scale framework and architecture migration. * Apply your deep .NET expertise to solve complex problems and see the direct results of your work on a critical application. * Work with a dedicated, multidisciplinary team of architects, engineers, and QA specialists. * Deepen your expertise in both legacy and modern .NET ecosystems, becoming an authority on complex modernization patterns. * Be part of a quality first company, multiple options for getting new education and certifications. **We offer\*:** * Flexible working format \- remote, office\-based or flexible * A competitive salary and good compensation package * Personalized career growth * Professional development tools (mentorship program, tech talks and trainings, centers of excellence, and more) * Active tech communities with regular knowledge sharing * Education reimbursement * Memorable anniversary presents * Corporate events and team buildings * Other location\-specific benefits * not applicable for freelancers