What is the Accept header?

Accept is an HTTP header that tells a server which response media types the client can receive.

What can it tell you?

It may list text/html, application/json, image formats, and preferences. A server can use this for content negotiation but need not always return the first preference.

How NetKarte shows it

Open Client headers in the HTTP information card and read the Accept row. No input is needed: it automatically shows the raw value received for this request. Read media types together with q weights, keeping them separate from the response's Content-Type. If absent, it reports that it was not sent.

Notes

Accept alone cannot identify a browser or user. The same browser sends different values for navigation, API, and other request purposes.

Reading a q value

The illustrative value text/html, application/json;q=0.8, */*;q=0.1 prefers HTML, also accepts JSON, and gives other types a lower preference. Omitting q means a weight of 1. This is a format preference, not image quality or network speed.

image/* covers image types; */* covers all types. Listing a format does not mean the server has that representation available.

If the response format is unexpected

1. Use NetKarte to see the Accept received for this request.
2. On the affected site, select the relevant request in browser developer tools.
3. Compare its request Accept with the response Content-Type.

NetKarte does not fetch other sites' responses. Header length and the number of formats are not measures of browser performance.