AddThis.com Widget Privacy Warning
Oct 9th, 2025 by Viviane
I used to use the AddThis bookmarking widget, because it let users add content to many different services and didn’t look too cluttered.
My friend JC forwarded me an email from the WWWAC list. Addthis was bought by ClearSpring last month. Starting yesterday today, they are now slipping a ClearSpring Flash Tracker Object into all your pages. Like all flash trackers, these use cookie-busting LSOs to track users across all websites that utilize AddThis or ClearSpring technologies:
These cookies are not visible within user’s normal privacy options windows in their browsers and can not be cleared by using the browser’s Clear Private Data (Firefox) and similar privacy options. These cookies also work across all browsers on the machine as Flash stores these LSOs in a single location.
There’s more info at JohnHaller.com. He’s the author of the Portable Firefox program.
I’ve removed the widget from my blog and Lolita Wolf’s blog, and suggest you to do the same.
Balls, and I just got the damn thing working correctly too!
Ugh. I use this on a couple of my sites and it’s always made things so easy…and clean. So are these trackers there only when someone actually uses the widget….or does this effect every visitor to my pages?
@caracala The warning at John Haller’s site says:
“As with all flash tracking objects, the ClearSpring object uses Local Shared Objects aka “Flash Cookies” to track users as they visit multiple websites using AddThis or ClearSpring widgets.”
I think it affects all users who visit a site.