The 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 setRequestHeader()). The complementary server-side header of Access-Control-Allow-Headers will answer this browser-side header.
| Header type | Request header |
|---|---|
| Forbidden header name | yes |
Access-Control-Request-Headers: <header-name>, <header-name>, …
A comma-delimited list of HTTP headers that are included in the request.
Access-Control-Request-Headers: X-PINGOTHER, Content-Type
| Specification |
|---|
| Fetch Standard # http-access-control-request-headers |
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
Access-Control-Request-Headers |
4 |
12 |
3.5 |
10 |
12 |
4 |
2 |
Yes |
4 |
12 |
3.2 |
Yes |
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https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Request-Headers