See how much information your browser gives away at

Douglas Crawford

Douglas Crawford

July 10, 2014

It is truly amazing how much information a website can find out about you when you open its page in your browser. Not only do advertisers use all sorts of sneaky tricks to find out who you are, where you have been on the web, and where you are going, but the architecture of your browser itself can uniquely identify you though the process known as browser fingerprinting.

We have discussed browser fingerprinting in some depth before (including what measures you can take to reduce it), but it basically boils down to the fact that each browser, with its own preferences, set of plugins etc., if fairly unique, and can therefore be used to uniquely identify and track its user (the EFF’s Panopticlick website allows you see just how unique your browser is).


Your browser can in fact give away up to 50 bits of identifying information, and security researcher Henrik Gemal has put a website,, together that not only lists them, but provides a set of tools to test each potentially guilty element of your browser to see what information it is leaking.

Elements used to fingerprint your browser

  • Accepted File Types – which MIME types, charsets, encodings and languages your browser accepts
  • Active X – is ActiveX available and active in your browser?
  • Adobe Reader – is Adobe Reader installed, and if so which components are available?
  • Ajax Support and XML Information – is your browser capable of running Ajax and handling XML requests and documents (Ajax is a web development programming language)
  • Bandwidth – your connection speed can help identify you
  • Browser – shows which browser you are using, together with information such as codename, version, platform and online information
  • Colors – the colors your browser can display
  • Connections – the maximum number of connections your browser opens for a single hostname
  • Cookies – are cookies enabled, what type, and how many?
  • CPU – which CPU does your computer use?
  • CSS – which cascading style sheets (a web design element) does your browser support?
  • Cursors – what kind of cursor (the arrow type thing that shows where your mouse is pointing) does your browser support?
  • Date and Time – self-explanatory!
  • DirectX – does your browser support Microsoft’s DirectX APIs (used for graphics and multimedia). Only supported by Internet Explorer.
  • Do Not Track – most modern browsers support the option to request that websites don’t track you (a request that widely ignored). Have you turned this on?
  • .NET framework – does your browser support Microsoft’s .NET web development framework?
  • Email Verification – some mailservers are setup so that the validity of an email address can be verified
  • Flash – is Adobe Flash Player installed? Used for all sorts of web animation, interactive content and video playback, Flash is notoriously insecure
  • Fonts – obtainable through both Java and Flash plugins, the fonts installed in your system are a strong unique identifier
  • Google Gears – does your browser support outdated software used by Google to add new features to a browser
  • Gecko – does your browser support the open source Gecko rendering engine (used mainly in Mozilla products such as Firefox?)
  • Geolocation – does your browser allow your physical location to be pinpointed?
  • Google Apps – does your browser or computer support independently customizable versions of several Google products using a domain name provided by the customer?
  • GZip Support – GZip compression is often used on websites to lower the amount of data sent to the browser
  • IP Address – your uniqueinternet address (can be hidden using VPN)
  • Java – does your computer support thepopularJava programming language?
  • JavaScript – does your browser support the popular JavaScript web scripting language?
  • Languages – which languages have you installed your computer?
  • MIME Types – MIME types is a method used by browsers to associate files of a certain type with helper applications that display files of that type
  • Mobile – is your computer a mobile device (smart phone or tablet)
  • Objects – does your browser support various objects such as layers, images, forms, links, frames, anchors, etc.
  • Online / Offline – do you have an active internet connection?
  • OpenDNS – are you using the free, closed source OpenDNS DNS resolution service?
  • Operating System – are you using Windows, OSX, Linux, iOS, Android etc.
  • Plugins – a website can detect which browser plug-ins and extensions you have installed. This is a strong unique identifier
  • Proxy – is your internet connection running through a remote computer (proxy)?
  • Personal Security Manager/Security – Personal Security Manager (PSM) consists of a set of libraries that perform cryptographic operations on behalf of a client application (such as setting up an SSL connection, object signing and signature verification, and certificate management). Does your browser use PSM?
  • QuickTime Player – does your browser support Apple’s media player?
  • RealPlayer – does your browser support the RealNetworks media player, plus RealVideo and Real Jukebox (not many do these days)
  • Screen – shows information about your screen, including width, height, DPI, color depth, and font smoothing
  • Shockwave – is Adobe ShockPlayer installed, and if so which version and which components are available? ShockPlayer is designed to play Shockwave animations and interactive content, but this is rarely encountered these days
  • Silverlight – does your browser support Microsoft’s answer to Flash?
  • Sound Card – do you have a sound card installed in your computer
  • SVG – does your browser support Scalable Vector Graphics (SVG), an XML specification and file format for describing two-dimensional vector graphics, both static and animated?
  • Text Formatting – which formatting tags does your browser support? E.g. bold or italic.
  • VBScript – does your browser support Microsoft Visual Basic Scripting (most web pages use JavaScript instead)
  • WAP Device – is your mobile device WAP capable? (this is a very outdated technology)
  • WebKit – does your browser support the WebKit layout engine software component for rendering web pages in web browsers>
  • Windows Media Player – does your browser support Microsoft’s media player?

As you can see, your browser provides a great deal of information to websites. A lot of this information is used to improve your browsing experience (rendering fonts correctly, only showing content your browser is capable of displaying etc.), but it also allows advertisers and web analytics companies to uniquely identify you, and therefore track your movements as you surf the web (all the better to deliver targeted advertising to you).

Check out Panopticlick to see how unique your bowser is, and to test which of your browsers components are being used to identify you.

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