Senior Full Stack Developer - .NET / React Native Location: Chicago, IL (On-site) Contract: 1099 Type: Hire Start Date: ASAP Sphere partners with clients to transform their organizations by embedding technology and modern processes into everything they do. We enable lasting competitive advantage by combining global expertise and local insight. We are currently seeking a Senior Full Stack Developer with experience with .NET and React Native to join our team and help a financial services client enhance and expand their digital platforms. 📍 Please note: This role requires working on-site at the client’s office in Chicago, IL (hybrid) . Key Responsibilities * Design and build new APIs using .NET 6 / ASP.NET * Develop and maintain mobile applications using React Native * Collaborate closely with cross-functional teams including stakeholders, end users, and fellow engineers * Ensure application performance, scalability, and maintainability * Support ongoing development, testing, and deployment activities in a cloud-based environment Requirements * 5+ years of software development experience * Experience with .NET 6 / ASP.NET and C# * Experience with React Native for mobile development * Proficient in MySQL and Entity Framework * Experience with API design * Experience with RabbitMQ or other message brokers Nice to Have * Experience with AWS or other cloud platforms * Experience building UI test automation for React/React Native * Familiarity with CI/CD pipelines, containerization, or DevOps workflows * Background in financial services or regulated environments