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Track Web Visitors, Using Cross Browser Cookies, That Won’t Be Deleted
In: Development| JavaScript
28 Jun 2010OK, so the headline is a bit of an over statement, but for the vast majority of users on the net, this will be the case.
The theory is simple – use flash cookies for user tracking (in addition to normal cookies).
- Flash cookies are not controlled by the browser
- They cannot be deleted by the browser
- The only way to delete them, is by going to the Macromedia control panel
- Flash cookies are CROSS browser
- If I set a cookie in Internet Explorer, the value will instantly be available in Firefox, Chrome, Safari etc.
- Flash cookies can hold a LOT of information (100kb be default, up to umlimited)
- Flash cookies can have an unlimited life span
How many people do you know that have ever deleted their Flash Cookies?
(And how many of them are non-technical?)
For user tracking, this has immense capabilities. Providing you can create a UUID in JavaScript (you can), then you can track an unlimited number of people, and the vast majority of them will not have the knowledge to stop you tracking them.
This is nothing new, but I know that it’s not something that is normally employed.
Here are a few links for reading a bit more around the subject too:
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About this blog
The ramblings of Jon Reed. I am Developer at an international news corporation. Everyday I work with various technologies such as PHP, MySql, CSS, XHTML. I Love Web Development.
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- Jon Reed: That's the great thing about trying to track people this way. These cookies are detected/set/get all [...]
- Mike Pearce: Good post and some useful information. However, the biggest problem with use flash cookies is Apple. [...]
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- Mike Pearce: Great post mate, some advanced stuff. What do you suggest as an alternative to document.write(). [...]
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2 Responses to Track Web Visitors, Using Cross Browser Cookies, That Won’t Be Deleted
Mike Pearce
June 29th, 2010 at 9:55 am
Good post and some useful information. However, the biggest problem with use flash cookies is Apple. As they don’t support flash on iDevices, it’s impossible to use this method to track them (and, some other non-Apple mobile platforms too).
However, if you can come up with a combination flash-fall-back-to-browser cookie, then you’ve probably covered most of what you need to. Won’t be available across browsers though!
Jon Reed
June 29th, 2010 at 10:13 am
That’s the great thing about trying to track people this way. These cookies are detected/set/get all in javascript – all client side. You can detect & send the cookie to a tracking service. If the tracking service isnt sent one, then you can fall back to HTTP cookies.