See the HTTP request headers your browser sends: user agent, languages, client hints and more.
The headers your browser sends appear here as soon as they have been read.
Every time your browser asks a server for a page, an image or data, it sends request headers with it: who it is (User-Agent), which languages and formats it prefers (Accept-Language, Accept, Accept-Encoding), the client hints of Chromium browsers (Sec-CH-UA and the others), the Sec-Fetch headers that say what kind of request it is, and Do Not Track or Global Privacy Control when they are turned on. This page asks our server once after it opens and shows the headers of that request as they arrived, sorted by name.
Cookies and login headers (Cookie, Authorization, Proxy-Authorization and the header that carries a VLANlab API key) are never shown, so a cookie that the scripts of a page cannot read stays unreadable here too. The headers that Cloudflare and our own servers add on the way (every cf- and x-forwarded- header, X-Real-IP, CDN-Loop and True-Client-IP) are left out as well, because your browser did not send them. The answer goes only to you, with Cache-Control: private, no-store, and the headers are not stored.
The headers are read when the page opens. Press Check again after you change a browser setting or turn on an extension, a VPN or a privacy option, and compare. The headers of this request can differ a little from the ones sent for the page itself: a script request sends Accept: */* and Sec-Fetch-Mode: cors, where opening a page sends the page formats and navigate. Copy All puts the list on the clipboard as name: value lines.