I am using Chrome in linux with Version 51.0.2704.63 (64-bit). I recorded a HTTP request of Chrome and here is part of the recording:

User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.63 Safari/537.36

Why does Chrome send four browsers in the user-agent field? Is this a countermeasure to obfuscate the browser version?

1 Answer 1


Presumably you mean the following four:

  1. Mozilla/5.0 (X11; Linux x86_64)
  2. AppleWebKit/537.36 (KHTML, like Gecko)
  3. Chrome/51.0.2704.63
  4. Safari/537.36

most Web browsers use a User-Agent string value as follows:

Mozilla/[version] ([system and browser information]) [platform] ([platform details]) [extensions].
  • Mozilla is a byproduct of browser wars.

  • AppleWebKit/537.36 is the platform used by your browser.

  • Chrome/51.0.2704.63 is your browser

  • Safari/537.36 was added for historic reasons, where Safari was treated differently.

You may wish to also read this history or this SO post

  • 3
    Note, that since 2013 the platform Chrome uses is not WebKit, it's Blink, a fork of WebKit (which in it's turn is a fork of KHTML KDE lib)
    – Klesun
    Jan 16, 2020 at 23:27

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