Access-Control-Expose-Headers
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 |
Syntax
http
Access-Control-Expose-Headers: [<header-name>[, <header-name>]*]
Access-Control-Expose-Headers: *
Directives
- <header-name>
-
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 "*
".
Examples
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:
http
Access-Control-Expose-Headers: Content-Encoding
To additionally expose a custom header, like Kuma-Revision
, you can specify multiple headers separated by a comma:
http
Access-Control-Expose-Headers: Content-Encoding, Kuma-Revision
For requests without credentials, a server can also respond with a wildcard value:
http
Access-Control-Expose-Headers: *
A server can also respond with the *
value for requests with credentials, but in this case it would refer to a header named *
.
Specifications
Specification |
---|
Fetch Standard # http-access-control-expose-headers |
Browser compatibility
BCD tables only load in the browser