Sec-Fetch-Mode
Request headers
States whether the request is same-origin, CORS or a navigation.
| On the wire | Sec-Fetch-Mode: … |
|---|---|
| Category | Request headers |
Headers the browser attaches when it sends to the server.
How to read this
- The first digit of a status code carries the meaning: 4 means the request, 5 means the server.
- 404 means "not there"; 403 means "there, but not for you". Swapping them makes debugging slower.
- Header names are case-insensitive — Content-Type and content-type are the same header.
- Caching and CORS problems usually come down to one header line, visible in the browser’s network tab.
Frequently asked questions
Q. What does HTTP Sec-Fetch-Mode mean?
States whether the request is same-origin, CORS or a navigation.
Q. What does Sec-Fetch-Mode look like on the wire?
It travels as Sec-Fetch-Mode: …
Q. Where does Sec-Fetch-Mode appear?
In request headers.
Q. What group does Sec-Fetch-Mode belong to?
The request headers group; the rest of that group is listed further down.