The IE7 User-Agent String

In April 2005, we blogged about the new Internet Explorer 7 User Agent string sent to websites by the browser to identify itself.  Since our original blog posting, we have also posted two new articles on the topic to MSDN: Understanding User-Agent Strings, and Best Practices for detecting the Internet Explorer version.

A quick recap:

  • On Windows XP SP2, IE7 will send the following User-Agent header: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)
  • On Windows 2003 Server, IE7 will send the following User-Agent header: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.2)
  • On Windows Vista, IE7 will send the following User-Agent header: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0)

Over the last eighteen months, most sites that had previously blocked the new version of Internet Explorer have been updated, and we’re happy to report that the vast majority of Internet sites are now accessible using IE7.

There are a few remaining sites which fail to recognize IE7 because they are performing exact string matches to look for specific IE version strings. Those checks will need to be removed or updated to accommodate IE7. The Best Practice document linked above provides suggestions.

To enable you to workaround any remaining sites that block access to Internet Explorer 7, we developed the User Agent String Utility.  The utility comes in the form of a small executable that opens an IE7 instance that sends the IE6 user agent string.  It also provides a mechanism for you to report problem web sites to Microsoft so that we can follow up with the affected site owners.  Please download the tool and give it a try.

We look forward to your feedback!

Eric Lawrence