Origin
The Origin
request header indicates the origin (scheme, hostname, and port) that caused the request.
For example, if a user agent needs to request resources included in a page, or fetched by scripts that it executes, then the origin of the page may be included in the request.
Header type | Request header |
---|---|
Forbidden header name | yes |
Syntax
http
Origin: null
Origin: <scheme>://<hostname>
Origin: <scheme>://<hostname>:<port>
Directives
null
-
The origin is "privacy sensitive", or is an opaque origin as defined by the HTML specification (specific cases are listed in the description section).
<scheme>
-
The protocol that is used. Usually, it is the HTTP protocol or its secured version, HTTPS.
<hostname>
-
The domain name or the IP address of the origin server.
<port>
Optional-
Port number on which the server is listening. If no port is given, the default port for the requested service is implied (e.g., "80" for an HTTP URL) .
Description
The Origin
header is similar to the Referer
header, but does not disclose the path, and may be null
.
It is used to provide the "security context" for the origin request, except in cases where the origin information would be sensitive or unnecessary.
Broadly speaking, user agents add the Origin
request header to:
- cross origin requests.
- same-origin requests except for
GET
orHEAD
requests (i.e. they are added to same-originPOST
,OPTIONS
,PUT
,PATCH
, andDELETE
requests).
There are some exceptions to the above rules; for example, if a cross-origin GET
or HEAD
request is made in no-cors mode, the Origin
header will not be added.
The Origin
header value may be null
in a number of cases, including (non-exhaustively):
- Origins whose scheme is not one of
http
,https
,ftp
,ws
,wss
, orgopher
(includingblob
,file
anddata
). - Cross-origin images and media data, including that in
<img>
,<video>
and<audio>
elements. - Documents created programmatically using
createDocument()
, generated from adata:
URL, or that do not have a creator browsing context. - Redirects across origins.
- iframes with a sandbox attribute that doesn't contain the value
allow-same-origin
. - Responses that are network errors.
Referrer-Policy
set tono-referrer
for non-cors
request modes (e.g. simple form posts).
Note: There is a more detailed listing of cases that may return null
on Stack Overflow: When do browsers send the Origin header? When do browsers set the origin to null?
Examples
http
Origin: https://developer.mozilla.org
http
Origin: http://developer.mozilla.org:80
Specifications
Specification |
---|
The Web Origin Concept # section-7 |
Fetch Standard # origin-header |
Browser compatibility
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