I'm analyzing user agent field of different types of web server logs. Ex. Apache Access Log/W3C/iplant etc. I found some lines in the log files have following type of user agents. I'm confused since it has many of the browser signatures.

Can somebody please explain what does following user agent means?

"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.31 (KHTML, like Gecko) Chrome/26.0.1410.64 Safari/537.31"


Chrome 26.0 on Windows 7 x64 sends that

I have no idea why it sends such an ambigious User-Agent string

  • Browsers are sending more and more ambiguous user agent strings to avoid browser sniffing scripts. – ceejayoz Jul 11 '13 at 14:05
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    Chrome is based on WebKit (based on KHTML, formerly Konquorer Web Browser, based on Mozilla's rendering engine, now called Gecko) an Apple project to strip the rendering engine out of the aforementioned software for use in Safari. Why they need to mention all that history in the most esoteric way possible is because some WebDevs tend to be spoon-lickers, and even modern web browsers aren't all HTML (pick a spec, and spec) compatible (notable IE usually the glue-eater, and everyone else is much more similar). – Chris S Jul 11 '13 at 14:12
  • aka it's a legacy thing – Mathias R. Jessen Jul 11 '13 at 14:12
  • @Mathias R. Jessen: Ok Is it always the case? I mean the above user agent string is generated only from Chrome 26.0 on Windows 7 x64? – Nilani Algiriyage Jul 11 '13 at 14:14
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    Yes, it would be minorly differ on other version of Windows (the "Windows NT 6.1" == Win 7; "WOW64" == "32bit Chrome on 64bit host OS). – Chris S Jul 11 '13 at 14:20

Because user agent sniffing is useless.

In the beginning there was NCSA Mosaic, and Mosaic called itself NCSA_Mosaic/2.0 (Windows 3.1), and Mosaic displayed pictures along with text, and there was much rejoicing.

And behold, then came a new web browser known as “Mozilla”, being short for “Mosaic Killer,” but Mosaic was not amused, so the public name was changed to Netscape, and Netscape called itself Mozilla/1.0 (Win3.1), and there was more rejoicing. And Netscape supported frames, and frames became popular among the people, but Mosaic did not support frames, and so came “user agent sniffing” and to “Mozilla” webmasters sent frames, but to other browsers they sent not frames.

Copied from http://webaim.org/blog/user-agent-string-history/ where you can also find the full story, incuding the Chrome User-Agent string.


Webkit-based browsers (Chrome/Safari) send that browser string (Safari omits the Chrome part).

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