The Access-Control-Expose-Headers response header allows a server to indicate which response headers should be made available to scripts running in the browser, in response to a cross-origin request.
Only the CORS-safelisted response headers are exposed by default. For clients to be able to access other headers, the server must list them using the Access-Control-Expose-Headers header.
| Header type | Response header |
|---|---|
| Forbidden header name | no |
Access-Control-Expose-Headers: [<header-name>[, <header-name>]*] Access-Control-Expose-Headers: *
A list of zero or more comma-separated header names that clients are allowed to access from a response. These are in addition to the CORS-safelisted response headers.
* (wildcard)The value "*" only counts as a special wildcard value for requests without credentials (requests without HTTP cookies or HTTP authentication information). In requests with credentials, it is treated as the literal header name "*" without special semantics.
The CORS-safelisted response headers are: Cache-Control, Content-Language, Content-Length, Content-Type, Expires, Last-Modified, Pragma. To expose a non-CORS-safelisted response header, you can specify:
Access-Control-Expose-Headers: Content-Encoding
To additionally expose a custom header, like Kuma-Revision, you can specify multiple headers separated by a comma:
Access-Control-Expose-Headers: Content-Encoding, Kuma-Revision
For requests without credentials, a server can also respond with a wildcard value:
Access-Control-Expose-Headers: *
However, this won't wildcard the Authorization header, so if you need to expose that, you will need to list it explicitly:
Access-Control-Expose-Headers: *, Authorization
| Specification |
|---|
| Fetch Standard # http-access-control-expose-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-Expose-Headers |
4 |
12 |
3.5 |
10 |
12 |
4 |
2 |
Yes |
4 |
12 |
3.2 |
Yes |
wildcard |
65 |
79 |
69 |
No |
52 |
No |
65 |
65 |
No |
47 |
No |
9.0 |
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https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Expose-Headers