Senior .NET / React Developer - Global Markets Inside IR35 Contract Role - London - Up to £850 per day About the Role: We are currently seeking an experienced Senior .NET Developer to join a leading global financial institution in London. This is a 6-month contract with strong likelihood of extension, working on critical desktop applications within their Global Markets technology team. Key Responsibilities Enhance and maintain two business-critical desktop applications: A desktop application launcher/management system built with WPF and .NET A background business alerting application that processes system events Develop new React admin screens as part of extending these applications to new business units Participate in architecture improvements to support broader deployment Work closely with a small, collaborative development team Technical Requirements Strong experience with .NET development and React Familiarity with event processing systems and messaging architectures Ability to work across both frontend and backend development The Ideal Candidate Will Have Strong understanding of event-driven architectures Experience with asynchronous programming and multi-threading Exposure to financial services applications (though deep domain knowledge is not required) Ability to work independently in a small team environment Work Environment Hybrid working arrangement: 50% office time (3 days one week, 2 days the next) Small, collaborative team of 3 developers based in London Contract Details Day rate: Up to £850 per day Duration: 6 months initial term with expected extensions Location: London office If you're an experienced .NET developer looking for a varied and technically challenging role within financial technology, we'd love to hear from you.