Note: As of October 2015 Twitter is phasing out their share counters, so those are no longer available.
Counter values are stored by the various services based on the URL of the page. If any of the underlined elements in this example URL are different between pages the counter values will be different.
So the URLs
http://www.example.com/ will have different counts, as will the URLs
http://www.example.com/index.html, even if they go to the same page.
To prevent this, you can set the URL to share. The easiest way to do this, and the one with the added benefit of improving your SEO, is to set a canonical link tag in your header. Another solution is to use the addthis:url attribute in the toolbox
<div> to set the URL that is shared to the URL you want. Here’s an example:
<div class="addthis_toolbox addthis_default_style " addthis:url="http://www.example.com/">
What counter values mean
Many people make the common mistake of thinking the Facebook Like button should have the same number of fan Likes on their Facebook Page. This isn’t true. The Facebook Like button doesn’t count Likes for your Facebook Page, and the Google +1 button doesn’t count the number of people who have +1’ed your Google+ Page. The Like/+1 button counters specifically show the number of times the URL (the one you’ve configured to share) has been shared to those services. Many counters, including the Facebook Like button counter and Tweet button counter also include activity not tracked by AddThis analytics, such as likes, shares, and comments that happen on Facebook.com. Here’s a screenshot of what you’d see about your Facebook-related activity from your AddThis analytics page:
Where counter values are stored
Each service — whether that’s Facebook, Google+, or AddThis — stores its counter values separately. This means that the value you see in Facebook’s Like counter is only stored on Facebook’s servers, not AddThis servers. The same goes for the Tweet, +1, and all of our third-party buttons. So when you see that your counter reset without having made any changes to your URL, it’s almost always something that happens outside of the AddThis tool.
Counters are also served from cached servers to improve performance. So, for instance, you share something to Facebook, and then immediately refresh your page, the counter won’t be updated until Facebook’s counter server updates its cache. AddThis counters work a little differently. We cache the values, but we also store the counter value in a cookie on your computer after you share, so users are reassured their share was registered.
The only counter values AddThis stores are the ones used in our compact menu and our pill-style menu. That is, for:
<a class="addthis_counter addthis_pill_style"></a>
<a class="addthis_counter addthis_bubble_style"></a>
Our Individual Share Counters use the services’ APIs to get the counts, so we don’t store those counter values on our servers either.