The Sec-Fetch-Mode fetch metadata request header indicates the mode of the request.

Broadly speaking, this allows a server to distinguish between: requests originating from a user navigating between HTML pages, and requests to load images and other resources. For example, this header would contain navigate for top level navigation requests, while no-cors is used for loading an image.

Header type Fetch Metadata Request Header
Forbidden header name yes (prefix Sec-)
CORS-safelisted request header no


Sec-Fetch-Mode: cors
Sec-Fetch-Mode: navigate
Sec-Fetch-Mode: no-cors
Sec-Fetch-Mode: same-origin
Sec-Fetch-Mode: websocket

Servers should ignore this header if it contains any other value.



These directives correspond to the values in Request.mode.

The request is a CORS protocol request.
The request is initiated by navigation between HTML documents.
The request is a no-cors request (see Request.mode).
The request is made from the same origin as the resource that is being requested.
The request is being made to establish a WebSocket connection.


If a user clicks on a page link to another page on the same origin, the resulting request would have the following headers (note that the mode is navigate):

Sec-Fetch-Dest: document
Sec-Fetch-Mode: navigate
Sec-Fetch-Site: same-origin
Sec-Fetch-User: ?1

A cross-site request generated by an <img> element would result in a request with the following HTTP request headers (note that the mode is no-cors):

Sec-Fetch-Dest: image
Sec-Fetch-Mode: no-cors
Sec-Fetch-Site: cross-site


Fetch Metadata Request Headers (Fetch Metadata)
# sec-fetch-mode-header

Browser compatibility

BCD tables only load in the browser

See also