Describe the problem/error/question
I have a workflow which runs though several URLs, each URL has its own Header Auth.
How can I program the HTTP Request node to use a specific Auth for the specific URL using Expression?
Hi @alwynispat 
Welcome to the community 
I just gave this a go with this workflow, using webhook.site to test:
In the Set node, we’re setting our header secret to a variable called “mySecret”. Meanwhile, in HTTP request node credentials header auth, we’re using the expression {{ $json["mySecret"] }} to use whatever is in the Set node, like this:
The headers used in the first request were this:
And the headers used in the second request were this when changing the value in the Set node:
Hope that example helps!