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/HTTP

Access-Control-Allow-Credentials

The Access-Control-Allow-Credentials response header tells browsers whether to expose the response to frontend JavaScript code when the request's credentials mode (Request.credentials) is include.

When a request's credentials mode (Request.credentials) is include, browsers will only expose the response to frontend JavaScript code if the Access-Control-Allow-Credentials value is true.

Credentials are cookies, authorization headers or TLS client certificates.

When used as part of a response to a preflight request, this indicates whether or not the actual request can be made using credentials. Note that simple GET requests are not preflighted, and so if a request is made for a resource with credentials, if this header is not returned with the resource, the response is ignored by the browser and not returned to web content.

The Access-Control-Allow-Credentials header works in conjunction with the XMLHttpRequest.withCredentials property or with the credentials option in the Request() constructor of the Fetch API. For a CORS request with credentials, in order for browsers to expose the response to frontend JavaScript code, both the server (using the Access-Control-Allow-Credentials header) and the client (by setting the credentials mode for the XHR, Fetch, or Ajax request) must indicate that they’re opting in to including credentials.

Syntax

Access-Control-Allow-Credentials: true

Directives

true
The only valid value for this header is true (case-sensitive). If you don't need credentials, omit this header entirely (rather than setting its value to false).

Examples

Allow credentials:

Access-Control-Allow-Credentials: true

Using XHR with credentials:

var xhr = new XMLHttpRequest();
xhr.open('GET', 'http://example.com/', true); 
xhr.withCredentials = true; 
xhr.send(null);

Using Fetch with credentials:

fetch(url, {
  credentials: 'include'
})

Specifications

Specification Status Comment
Fetch
The definition of 'Access-Control-Allow-Credentials' in that specification.
Living Standard Initial definition

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
Access-Control-Allow-Credentials 4 12 3.5 10 12 4
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
Access-Control-Allow-Credentials 2 Yes 4 12 3.2 Yes

See also

© 2005–2020 Mozilla and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Credentials