C# Senior Software Developer - Onsite

C# Senior Software Developer - OnsiteMy 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 ResponsibilitiesDevelop and maintain web portals using ASP.NET MVC / .NET CoreDesign and integrate REST APIs with internal and third-party servicesImplement 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 → ResponseMaintain and publish API documentation via Swagger / OpenAPIEnsure API security, reliability, and performance (error handling, retry logic, logging, timeouts, CORS)Collaborate with database, infrastructure, and QA teams for portal and API releasesParticipate in code reviews, version control, and CI/CD deployment workflowsRequired Technical SkillsC# (strong proficiency)ASP.NET MVC or .NET Core Web APIMVC concepts: Routing, Controllers, Filters, Middleware, Model Binding, Dependency InjectionEntity Framework Core (DbContext, DbSet, OnModelCreating, LINQ) and ADO.NET/Raw SQL experienceMS SQL Server or MySQL database experienceHTML5, CSS3, JavaScriptREST 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 KestrelDocker basics (preferred but not mandatory)Preferred/Bonus SkillsExperience with fintech or payments API integrationCloud services (Azure, AWS) hosting basicsWebhooks and event-based APIsStructured logging tools (Splunk, ELK, App Insights)Performance optimization and API rate-handlingWhy Join My ClientBe part of a pioneering fintech/secure banking technology companyOpportunity to mentor and lead junior developersWork in a supportive, collaborative, and technically driven environmentGain experience in high-security, mission-critical software projectsInterested? Please Click Apply Now!C# Senior Software Developer