Senior .Net Engineer

Role Overview We are looking for a Senior .NET Engineer to work on migrating a client-facing e-commerce/store application's payment processing from its current gateway to a new payment provider. Key Responsibilities - Design and implement an abstraction layer that decouples the application from a single payment provider, enabling multiple providers to operate in parallel. - Implement the integration with the new payment provider, including the card-capture and payment/refund flows, in a way that minimizes the application's compliance exposure. - Collaborate closely with a small delivery team and client-side stakeholders where ownership or documentation is incomplete. Requirements & Qualifications - Experience: 6+ years of professional .NET development on large production systems; brownfield / legacy modernization experience is mandatory — this is not a greenfield role. - Core stack (Must-Have): expert C# and ASP.NET (MVC, Web API, Razor Pages); hands-on with both .NET Framework 4.5.x-era code and .NET 6+ migrations; EF / EF Core. - Security mindset: practical experience remediating security findings (OWASP classes, secrets handling, crypto usage) in existing code; PCI / payments / fintech exposure is a strong plus. - Nice-to-Haves: Azure PaaS (App Services, Functions, Service Bus, Cosmos DB); AWS (Lambda, S3, SNS/SQS); Azure AD B2C; Blazor; SignalR; Telerik / Kendo UI. - English: fluent written and spoken English (B2+) for documentation, evidence packages and client calls. 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