How to add custom header to asp net core web api response


ASP.NET is a popular programming language used for building web applications. One requirement in web is the need to add custom headers to the HTTP response of an ASP.NET Core Web API. In this article, we will explore how to achieve this ASP.NET Core.

Adding Custom Headers

To add a custom header to the ASP.NET Core Web API response, we can leverage the middleware pipeline provided by the . Middleware components are responsible for processing HTTP requests and responses.

To add a custom header, we need to create a middleware component that intercepts the response and adds the desired header. Let's take a look at an example:

public class CustomHeaderMiddleware
    private readonly RequestDelegate _next;

    public CustomHeaderMiddleware(RequestDelegate next)
        _next = next;

    public async Task Invoke(HttpContext context)
        context.Response.Headers.Add("Custom-Header", "Custom Value");
        await _next(context);

In the above example, we create a middleware component called CustomHeaderMiddleware. This component takes in a RequestDelegate in its constructor, represents the next middleware component in the pipeline.

The Invoke method is where we add the custom header to the response. We access the Response property of the HttpContext and use the Headers property to add the custom header with a desired value.

Finally, we call the next middleware component in the pipeline using the await _next(context) to ensure the request continues to be processed by the subsequent middleware components.

Registering the Middleware

Once we have created the custom middleware component, we need to register it in the ASP.NET Core application's startup class. Let's see how this can be done:

public class Startup
    public void Configure(IApplicationBuilder app)
        // Other middleware registrations

In the Configure method of the startup class, we use the UseMiddleware extension method to register our custom middleware component. This ensures that the middleware is executed for every incoming request.

It is important to note that the order of middleware registration matters. The custom middleware be registered before any middleware that might modify the response headers, such as authentication or middleware.


Adding custom headers to an ASP.NET Core Web API response is a common requirement in web development. By leveraging the middleware pipeline and creating a custom middleware component, we can easily add custom headers to the HTTP response. This allows us to customize the behavior and enhance the functionality of our web applications.

By following the steps outlined in this article, you should now have a good of how to add custom headers to an ASP.NET Core Web API response using ASP.NET programming language.

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