Adding headers when using httpClient.GetAsync

A later answer, but because no one gave this solution...

If you do not want to set the header on the HttpClient instance by adding it to the DefaultRequestHeaders, you could set headers per request.

But you will be obliged to use the SendAsync() method.

This is the right solution if you want to reuse the HttpClient -- which is a good practice for

• performance and port exhaustion problems
• doing something thread-safe
• not sending the same headers every time

Use it like this:

using (var requestMessage =
            new HttpRequestMessage(HttpMethod.Get, "https://your.site.com"))
{
    requestMessage.Headers.Authorization =
        new AuthenticationHeaderValue("Bearer", your_token);
    
    await httpClient.SendAsync(requestMessage);
}

When using GetAsync with the HttpClient you can add the authorization headers like so:

httpClient.DefaultRequestHeaders.Authorization 
                         = new AuthenticationHeaderValue("Bearer", "Your Oauth token");

This does add the authorization header for the lifetime of the HttpClient so is useful if you are hitting one site where the authorization header doesn't change.

Here is an detailed SO answer