What Should a C# Developer Know About REST API Integration Before Starting a Full Stack Job?

A C# developer should understand REST integration at both the consumer and API-design levels. Simply knowing how to send an HTTP request is not enough for enterprise application development. At the protocol level, developers should be comfortable with HTTP methods, status codes, headers, content negotiation, JSON serialization, authentication, authorization, pagination, filtering, versioning, and idempotency. They should understand why GET, POST, PUT, PATCH, and DELETE have different semantics and how incorrect usage can create integration problems. In .NET, developers should be comfortable using HttpClient through IHttpClientFactory, configuring named or typed clients, handling timeouts, cancellation tokens, transient failures, retries, and structured logging. They should also understand how to deserialize external responses safely and validate both successful and unsuccessful responses. Enterprise integration requires deeper thinking. What happens if the downstream API is unavailable? What if it returns a 429? What if a request succeeds but the client never receives the response? How should duplicate requests be handled? How should sensitive information be logged? These questions lead into resilience patterns, retry policies, circuit breakers, idempotency, correlation IDs, and observability. A strong full-stack developer should also know how to design their own REST APIs using DTOs, validation, consistent error responses, authentication/authorization, API versioning, OpenAPI/Swagger, and clean separation between controllers, business logic, and data access. For students building portfolios, integrating a .NET application with one or two realistic external APIs—and handling authentication, failures, pagination, validation, and logging—is an excellent way to demonstrate production-oriented development skills.