Can I hide an API Key used in the request header

I set up Postmark using the HTTP request node.

The Postmark documentation says that the API key needs to be added as a request header. I hard-coded the API key in the request header and it works fine, however, I was wondering if there’s a way to store it as a “secret” variable in n8n so that if I share the workflow via JSON I won’t be exposing my API key?

Yes, you can remove it from the header and then set “Authentication” to “Header Auth”. There you can then set the header-key (parameter: Name) and the value (parameter: Value) there.