Access-Control-Request-Headers

{{HTTPSidebar}} 

The HTTP Access-Control-Request-Headers {{Glossary("request header")}}  is used by browsers when issuing a {{glossary("preflight request")}}  to let the server know which HTTP headers the client might send when the actual request is made (such as with {{domxref("Window/fetch", "fetch()")}}  or {{domxref("XMLHttpRequest.setRequestHeader()")}} ). The complementary server-side header of {{HTTPHeader("Access-Control-Allow-Headers")}}  will answer this browser-side header.

Syntax

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

Access-Control-Request-Headers: content-type,x-pingother

Specifications

{{Specifications}} 

Browser compatibility

{{Compat}} 

See also

• {{HTTPHeader("Access-Control-Request-Method")}}