Comparison Of Private Browsing In IE, Chrome and Firefox

Private Browsing is a privacy feature in web browsers designed to leave no easily detectable evidence of your browsing and search history. It therefore helps prevent anyone else who uses your computer from seeing which webpages you visited and what content you viewed.

Browser developers suggest that Private Browsing is therefore most useful when ‘shopping for a birthday present’ – bless ’em.

The fact that it is more commonly known as ‘P0rn Mode’ or ‘Man’s Best Friend’ may give a typical indication of its usage – by people who don’t want to be caught with their trousers down…

Private Browsing Feature Comparison – The major browsers each have their own version of it:

  • Firefox – Private Browsing
  • Internet Explorer – InPrivate Browsing
  • Chrome – Incognito Mode

As you might expect, a comparison of their features reveals that they are very similar:

private browsing

Key Differences Between The Browsers

1. History of visited pages – IE

Although IE InPrivate Browsing doesn’t save visited pages in the usual locations, it does continue to save every website you visit to the special index.dat files. Whilst these index.dat database files can’t be read just by opening them, various programs like index.dat suite are able to read them and display the history data.

IE therefore falls down on privacy as it is possible (though difficult) to retrieve all the pages you visited during an InPrivate Browsing session.

2. Extensions/Addons Disabled by default – Firefox

Firefox does not disable addons (extensions) by default whereas IE and Chrome do (although you can re-enable them). As the web browser can’t control how addons/extensions handle your personal data it is safer to disable them by default as they could potentially store records of your web browsing history/cookies etc.

Firefox therefore falls down slightly on potential privacy – although it could be difficult to find or read any such records stored by an addon and I’m not aware of any popular ones that do actually store such data.

3. Start every session in Private Browsing mode – Chrome and IE

This is not a privacy feature as such but Firefox offers a simple menu option to let you always start every session in Private Browsing mode. Chrome and IE require a command line shortcut to be used (W7 users can also start IE in InPrivate Browsing mode by right-clicking on the IE icon in the taskbar).

Other Privacy Risks

All three browsers allow the use of Plugins in private browsing – examples of plugins include Flash Player and Java. Plugins may be a risk because they could contravene the privacy mode of the web browser i.e. leave behind a trail of cookies or visited sites.

E.g. old versions of Adobe Flash Player used to store special ‘Flash’ cookies that persisted even if all internet history and cookies were supposedly deleted – Flash Player 11 no longer does this.


None of these Private Browsing tools stop websites seeing and recording your visits – they only protect your local privacy i.e. protect your browsing history data from other people who may use your computer.

How Safe Is Private Browsing?

All the browsers do a good job of hiding your internet tracks from anyone else using the same computer – if they have a casual interest or just peek in the usual locations where history and other tracks are usually stored.

There should certainly be no obvious evidence of your website history if using Private Browsing. However, more determined or knowledgeable users might be able to exploit your use of IE due to the privacy risk of index.dat files.

Firefox itself is as private as Chrome but leaving all addons enabled by default is a slight risk. However, Chrome users could choose to enable extensions in Incognito Mode anyway – e.g. safe search software like Web Of Trust etc.

Apart from privacy aspects, remember that searching for p0rn is much like real life – if you visit acres of flesh you will likely get infected by a virus sooner rather than later…

For illustrated guides to how to turn on or turn off Private Browsing features see the following:

Firefox Private Browsing – see Mozilla’s guide here.

Chrome Incognito Mode – see Google’s guide here.

Internet Explorer InPrivate Browsing – see Microsoft’s guide for Internet Explorer.