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How to remove User-Agent for Firefox

The goal is to remove this header from all web requests, in case you don't want sites to know which OS are you using.

fixer1234
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VasyaNovikov
  • 3,656

3 Answers3

13

There is a way to do this without any addons:

  • enter "about:config" into the URL bar. Press Enter.
  • create a new entry with key=general.useragent.override and an empty string as a value.
  • If you use an old version of Firefox, you also need to set the key general.useragent.enable_overrides to true.

This way your browrer will not send any "User Agent" at all. You can check this by doing:

  • open firefox network view with Ctrl Shift Q
  • load any URL you want
  • click on a web request and see the "Request Headers" on the right. There should be no "User-Agent" entry if you've done it right.

P.S. Your browser may still be leaked if you have JS enabled for a site. This is because each browser has its own rendering capabilities, supported formats etc. The described steps remove "User-Agent" request headers, that's all.

VasyaNovikov
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0

I use an add-on for this, but only for specific websites that should treat me as a mobile device...

With Modify Headers you can try to fix your problem: https://addons.mozilla.org/de/firefox/addon/modify-headers/

MushyPeas
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Note that it is still recommended to leave a minimum useragent string (e.g.: Mozilla/5.0), otherwise some sites (I won't give names) will totally block access...

Strahd Ivarius
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