6.62HttpClientHandler Underlying Handler for Sending Requests

Created on Aug 17, 2026~3 min read

HttpClientHandler is the core message handler in .NET used to configure and execute actual HTTP requests. It is a concrete implementation class of HttpMessageHandler, typically serving as the last stage of the HttpClient message processing pipeline, and is responsible for interacting with the operating system's network layer to complete the actual sending of HTTP requests and receiving of responses.

Although both DelegatingHandler and HttpClientHandler inherit from HttpMessageHandler, they have clearly distinct responsibilities:

  • DelegatingHandler: Used to build pluggable, chained middleware logic (such as logging, authentication, retry, and so on). It does not initiate network requests directly; instead, it delegates the request to the next handler.
  • HttpClientHandler: Is the handler that ultimately executes network I/O, encapsulating platform-specific underlying implementations (such as WinHTTP, libcurl, or SocketsHttpHandler), and provides rich configuration options to control connection behavior, security policies, proxy settings, and more.