We are looking for a highly skilled Senior C# ASP.NET Core Developer to join our client’s team on a long‑term freelance contract. The role focuses on building high‑performance, scalable applications in the Temporary Work and Payroll sector. You will design and optimize data models, implement asynchronous services, and ensure code quality through unit testing. Fluency in French is required, and experience with PostgreSQL, Entity Framework Core, and modern .NET practices is essential.