How to View HTTP Headers

HTTP headers precede the fetching of a website.

HTTP headers are sent by your browser when a page is first contacted. There is sometimes confusion between HTTP headers and the "HEAD" section in an HTTP web page. HTTP headers are meant to inform the website of the browser's capabilities. The website will send back its headers in response. There are two ways of viewing HTTP headers. The first is to visit a website that is designed to show them. The other is to install an add-on for your browser that will show the HTTP headers for each transaction.

Instructions

Displaying Website

1. Visit a header viewer website. There are a number listed in Resources (below). Some sites automatically display the headers from your browser, and so no further action is needed. Others will require further action.

2. Enter the address of the website you would like to contact in order to display the headers. The viewing site may offer a number of parameters for the transaction: what version of HTML you want to see the headers for and what kind of request should be sent to view the headers are two examples.

3. Switch between viewing the headers sent by your browser and headers on the response from the server. Some sites will show both on the same page; some sites will have different pages for the two sets of headers. Other sites will only show the headers from your browser, but will give a link to a site where the server headers can be viewed.

Live HTTP Headers 0.16 for Mozilla Firefox

1. Download the add-on from the Mozilla website. Press the "Download Now" button on the page detailing the add-on (see Resources). When the download is complete, open the file to run it. The add-on will be installed.

2. Open your Firefox browser and enter an address in the address bar. Press "Enter."

3. Examine the headers in the "Live Headers" window. Headers sent by your browser and on the response from the server will be shown.

ieHTTPHeaders for Internet Explorer

1. Download the plugin from the Blunk website (see Resources). Press the "Download" button on the ieHTTPHeaders page. When the download is complete, open the file to run it. The plug-in will be installed.

2. Open Internet Explorer and enter an address in the address bar. Press "Enter."

3. Examine the headers in the ieHTTPHeaders window. This will show headers sent by your browser and the websites you visit.

References

• PLG: HTTP Header Viewer

Resources

• Web Sniffer: View HTTP Request and Response Header
• iWebTool: HTTP Headers
• Mozilla: Add-ons for Firefox: Live HTTP Headers0.16
• Jonas Blunck: ieHTTPHeaders