Mid-level full-stack .NET developer in Cardiff who designs, builds and maintains ASP.NET Core (C#) web applications with complex business logic, SQL Server/EF Core data access, and REST/SOAP third-party integrations. Frontend work uses Razor Pages, jQuery, Data Tables and AJAX, with AI-assisted development workflows encouraged.
We are seeking a highly analytical and solutions-driven Mid Level Full Stack .NET Developer to design, develop, and maintain scalable web applications with complex business logic and third-party integrations.
This role combines backend engineering, frontend development, and intelligent automation practices that include using AI-assisted development workflows to improve efficiency, code quality, and architectural decision-making.
Key Responsibilities
Design and maintain ASP.NET Core applications using C#
Implement complex LINQ queries and EF Core data access patterns
Optimise database interactions and query performance
Build and maintain REST and SOAP integrations with external providers
Implement robust logging, validation, and exception handling
Frontend Development
Manage conditional UI rendering based on business rules
Ensure smooth client-side/server-side integration
System Architecture & Business Logic
Translate complex business requirements into maintainable code
Maintain separation of concerns across services and UI layers
Improve reliability of provider communications and validation workflows
Technical Skills
Core Stack
C# / .NET Core MVC
Entity Framework Core
SQL Server
LINQ
Frontend
Razor Pages / MVC
jQuery
Data Tables
AJAX
Integration & Data
SOAP services
REST APIs
Logging and diagnostics
Repository / Service patterns
Performance optimization
Business rule modelling
Strong problem solver with attention to edge cases
Detail-oriented in both backend logic and UI behaviour