index.md

---

title: Access-Control-Request-Headers
slug: Web/HTTP/Headers/Access-Control-Request-Headers
browser-compat: http.headers.Access-Control-Request-Headers

---

{{HTTPSidebar}}

The Access-Control-Request-Headers 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("XMLHttpRequest.setRequestHeader()","setRequestHeader()")}}). The complementary server-side header of {{HTTPHeader("Access-Control-Allow-Headers")}} will answer this browser-side header.

Header type	{{Glossary("Request header")}}
{{Glossary("Forbidden header name")}}	yes

Syntax

Access-Control-Request-Headers: <header-name>, <header-name>, …

Directives

• <header-name>

  • : A comma-delimited list of HTTP headers that are included in the request.

Examples

Access-Control-Request-Headers: X-PINGOTHER, Content-Type

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

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