C# Senior Software Developer My client is seeking a talented C# Senior Softwar 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.NET MVC or .NET Core Web API MVC concepts: Routing, Controllers, Filters, Middleware, Model Binding, Dependency Injection Entity Framework Core (DbContext, DbSet, OnModelCreating, LINQ) and ADO.NET/Raw SQL experience MS SQL Server or MySQL database experience HTML5, CSS3, JavaScript REST API expertise and integration (HttpClient, RestSharp, JSON serialization/deserialization, CORS, HTTPS, API security) Git version control and CI/CD workflows (Azure DevOps, GitLab CI preferred) Hosting experience with IIS or Kestrel Docker basics (preferred but not mandatory) Preferred/Bonus Skills Experience with fintech or payments API integration Cloud services (Azure, AWS) hosting basics Webhooks and event-based APIs Structured logging tools (Splunk, ELK, App Insights) Performance optimization and API rate-handling Why Join My Client Be part of a pioneering fintech/secure banking technology company Opportunity to mentor and lead junior developers Work in a supportive, collaborative, and technically driven environment Gain experience in high-security, mission-critical software projects Interested? Please Click Apply Now!C# Senior Software Developer