Live HTTP headers Firefox extension

I recently needed a tool that would enable me to view all http requests issued by the Web page loaded in my browser — in order to figure out what files were being requested and from which location. For those of you in a similar situation, I strongly recommend the LiveHTTPHeaders Firefox extension.

The tool is great, works on multiple platforms, and gets around needing to install and configure a packet sniffer in order to gain this type of information.

As described on the LiveHTTPHeaders project Web site:

The goal of this project is to adds information about the HTTP headers in two ways:

  • First by adding a ‘Headers’ tab in ‘View Page Info’ of a web page.
  • Second by adding a tool in the ‘Tools->Web Development’ menu to be able to display http headers in real time (while pages are being downloaded from the Internet.
  • Third by letting you edit request headers and replay an URL (beta). Look for the Replay button in the live window!

This project may be of some help for the following:

  • Help debugging web application.
  • See which kind of web server the remote site is using.
  • See the cookies sent by remote site.

About LiveHTTPHeaders

LiveHTTPHeaders was developed by Daniel Savard along with contributions from Nikolas Coukouma. The software has been used by over 250,000 users and earned more than 100 positive reviews. Daniel has regularly updated this add-on since 2003 to extend compatibility to new releases of Mozilla-based web browser software – the most recent release, version 0.17, provided compatibility for Firefox 4.0 and Seamonkey 2.1. However, there are some reports that the extension causes some instability with Firefox 6 (which was officially released on August 16, 2011).

Daniel’s work has been integrated with CARENA, an extension for Mozilla Suite and Firefox web browsers for capturing and replaying web navigation. CARENA goes further by time stamping requests, completes additional parsing of HTTP headers, logs the method and version of each request, and enables automated playback of a web browsing session.

Learn more about Live HTTP Headers by visiting the official Firefox Add-Ons page or Daniel’s livehttpheaders project page on

Alternatives to the LiveHTTPHeaders Add-on

The Firebug add-on, developed by Joe Hewitt, Jan Odvarko, robcee, and the FirebugWorkingGroup provides an equivalent (and potentially better) method for reviewing HTTP requests. By clicking the “Net” menu in Firebug, you can log and review individual HTTP request, review the status of each request, see which domain each request was submitted to, sort by size of each request, view the remote IP address for where the resource was requested from, and see how many miliseconds the request took to fulfill. For more information about this extension, visit the official Firebug website.

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