Access-Control-Request-Headers header
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
The HTTP Access-Control-Request-Headers request header is used by browsers when issuing a preflight request to let the server know which HTTP headers the client might send when the actual request is made (such as with fetch() or XMLHttpRequest.setRequestHeader()). The complementary server-side header of Access-Control-Allow-Headers will answer this browser-side header.
| Header type | Request header |
|---|---|
| Forbidden request header | Yes |
Syntax
http
Access-Control-Request-Headers: <header-name>,<header-name>,…
Directives
<header-name>-
A sorted list of unique, comma-separated, lowercase HTTP headers that are included in the request.
Examples
http
Access-Control-Request-Headers: content-type,x-pingother
Specifications
| Specification |
|---|
| Fetch # http-access-control-request-headers |
Browser compatibility
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