Secret Agent Man

Just a quick one this morning as we all get started in the week. Something that comes into play (sometimes in a big way) is the user agent string your browser gives off. So for example using the User-Agent field in the request header, you can determine what browser the user is running and act accordingly.

Internet Explorer 9 modified the UA string slightly so just in case you're looking for it here are the user agent strings for IE9 (in various modes):

  • Internet Explorer 9 Mode: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)
  • Internet Explorer 8 Mode: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; MS-RTC LM 8; InfoPath.3; .NET4.0C; .NET4.0E; Zune 4.7)
  • Internet Explorer 7 Mode: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; WOW64; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; MS-RTC LM 8; InfoPath.3; .NET4.0C; .NET4.0E; Zune 4.7)
  • Internet Explorer 9 (Compatibility Mode): Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; WOW64; Trident/5.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; MS-RTC LM 8; InfoPath.3; .NET4.0C; .NET4.0E; Zune 4.7)

A couple of things to note here:

  • This was from a 64-bit Windows 7 client so that might account for the WOW64 in the agent string (I don't have a 32-bit client to test from)
  • Various applications and platforms add to the UA string just like they do in previous IE releases. So for example you can see I have various .NET versions installed as well as Zune. You can take advantage of this by querying the UA string for compatibilities and present options accordingly to the end user.
  • As applications will continue to add and modify this string you'll want to query the string for parts not the entire string. For example if you want to detect if you're coming from IE running  on a Windows Phone 7 just look for "iemobile" in the user agent string

Happy hacking!

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