Omnibug
Firefox Developer Tools
Google Chrome Developer Tools
TrueMetrics Analytics Inspector
ObservePoint
Tag Inspector
Code Cola
HTTP Header Live
WebSniffer
Modify Header Value (HTTP Headers)
HTTP-Repeater (HTTP/s Live Headers) (Beta)
Sky Live HTTP Headers
HTTP Header Spy
HTTP-TRACKER
Smart Header
HTTP Header Analyzer
WebSniffer is an intelligence platform in the making that is going to track changes on the web and provide actionable insights to its users. The online tool can currently view HTTP response headers of any web page, do domain name, IP address lookups and provides user’s browser information such as IP address, user agent and more.
Omnibug WebSnifferFirefox 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.
Google Chrome Developer Tools - Get started with Google Chrome's built-in web developer tools.
HTTP-Repeater (HTTP/s Live Headers) (Beta) - HTTP-Repeater (HTTP/s Live Headers) (Beta) is a browser extension that lets you capture browser requests and repeat the process in a loop automatically.
TrueMetrics Analytics Inspector - Analytics Inspector provides an easy way to validate web analytics and marketing integration, as well as offers a great way to quickly validate the instrumentation via the unique and simplified user interface.
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.