Add-ons like Flash and VLC and others are more obvious, and the general notion stands that “any add-on is a risk to make your online fingerprint unique”, but I'd still like to think a simple Appearance add-on might be retained internal to the code (although I know that even the window size you surf with is broadcast, and makes you stand out from the crowd. [Why on earth can't we override that window size value with a bland fake hard-coded value?)

Anyway, so specifically, will adding my favorite ~”SuperFudgeChunkPurpleMonkey”~ Appearance add-on from Mozilla.org leak to every website I visit? (Obviously I just made that name up, so don't go looking for it.)

Also – I like to customize and drag the Onion and NoScript buttons to the right side, and remove the Search bar entirely because I habitually use the URL box itself. May I assume that those three simple UI customizations are in no way exposed externally, making me a unique flower on the Internet horizon?


2 Answers 2


It seems that using a simple appearance add-on will not increase the uniqueness of your browser fingerprint (unless it weirdly modified any of the items below). No, moving those UI items shouldn't affect anything either.

Items contributing to uniqueness (https://wiki.mozilla.org/Fingerprinting):

  • plugins
  • fonts
  • user agent
  • http accept
  • screen resolution
  • timezone
  • supercookies
  • cookies

That being said, if javascript is enabled it may be possible for it to query that information (I'm not sure).

Also read: https://panopticlick.eff.org/browser-uniqueness.pdf

  • 1
    In response to the question in the title: I have no clue..
    – N10
    Commented Nov 18, 2015 at 10:01

NO, nearly everything you change can expose your uniqueness! heck also the used browser bars, your history or the number of open tabs can be tracked...!

that is why it is highly recommended to use Tails, the TBB or at least a TBB-profile!

at https://www.browserleaks.com/ you can read about a bunch of things which can be leaked by your browser...
or also try the test at http://ip-check.info to see some things of your browser that will be leaked!

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