Generate, review, and analyze HTTP headers for any web page. Check status code, response headers, redirect locations and more...
HTTP Header Live - Displays the HTTP header. Edit it and send it.
Firefox Developer Tools - Examine, edit, and debug HTML, CSS, and JavaScript on the desktop and on mobile.
Modify Header Value (HTTP Headers) - Modify Header Value (HTTP Headers) is a browser extension that allows you to add, modify or remove a header for any request to your preferred domains.
RequestHeaders.com - HTTP Header Checker Tools
Sky Live HTTP Headers - Sky Live HTTP Headers is an open-source browser extension that visually displays HTTP requests and response headers from every website you visit.
Fiddler - Fiddler is a debugging program for websites.