Changing Internet Explorer Browser Agent

Important note: These registry changes are provided as examples of how these parameters might be changed. Be sure you have a complete backup of your registry and an up-to-date ERD (Emergency Repair Disk) before you make any changes. The Registry editor can make your system unusable, so be careful! We take no responsibility for these registry changes - do them at your own risk!

As you surf the internet, you are leaving a little trail of breadcrumbs, telling everyone (well, webmasters) lots of information about your computer. Your browser informs their web server of things like your monitor size, resolution, browser type and version, and so on. The piece of information that tells them the browser type is called the User Agent field.

Under Internet Explorer, you can modify portions of the user agent field by editing the registry. You cannot change the entire field, but you can modify some of the parts. The User Agent for Internet Explorer has the following format until version 5.5.

Mozilla/4.0 (compatible; MSIE Ver; OperatingSystem; YourTag; YourNextTag)

In version 6.0, it was modified slightly:

Mozilla/4.0 (compatible; MSIE Ver; OperatingSystem; patchlevel; YourTag; YourNextTag)

In order to add your own tags to the end of the user agent, you can use the Registry Editor to modify the following key:

HKEY_LOCAL_MACHINE \Software \Microsoft \Windows \CurrentVersion \Internet Settings \5.0 \User Agent\

When I went to edit this on my own system, the key "User Agent" did not exist and I created it.

Under "User Agent", create the key "Post Platform". Now add a value (type REG_SZ). The name of the value is the text that will be added to the agent field. The actual data within the value is ignored. You may add more than one keys if you want.

The change shown below would add "http://www.internet-tips.net" to the User Agent, leaving a small advertisement for my web site in each webmaster's log file. 

The fully expanded log file entry looks something like:

Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; Q312461; http://www.internet-tips.net)

The Q312461 portion is new for Internet Explorer 6.0. It indicates the patch or service release level of the browser.