C# Senior Software Developer - Onsite My client is seeking a talented C# Senior Software Developer to join their Preston-based team. This role offers an exciting opportunity to lead projects, mentor junior developers, and work on high-impact, secure banking solutions. You will be a key contributor to web portal and API development, ensuring performance, security, and reliability in a dynamic environment. This role is ideal for developers with strong technical expertise who are looking to grow into leadership or team management responsibilities. Key Responsibilities Develop and maintain web portals using ASP.NET MVC / .NET Core Design and integrate REST APIs with internal and third-party services Implement secure authentication mechanisms (JWT, OAuth2, API Keys) Connect applications to relational databases using Entity Framework Core (DbContext, LINQ, Migrations) Debug and trace request flows from UI ? Controller ? API ? Database ? Response Maintain and publish API documentation via Swagger / OpenAPI Ensure API security, reliability, and performance (error handling, retry logic, logging, timeouts, CORS) Collaborate with database, infrastructure, and QA teams for portal and API releases Participate in code reviews, version control, and CI/CD deployment workflows Required Technical Skills C# (strong proficiency) ASP....