AddThis: The Tracker You Didn't Know About
Learn what AddThis was, how it collected data, and why blocking it is crucial for your privacy.
Drafted by automation from the sources listed at the end of this page, and reviewed before publishing. The sources are the part that matters: check them.
What is AddThis?
AddThis was a free social bookmarking service that allowed visitors of a website to share content across various social networks, such as Facebook, Twitter, and Pinterest, via a widget. However, in addition to facilitating sharing, AddThis also collected behavioral data from users, even when they did not share anything. The service reached 1.9 billion unique monthly visitors and was used by more than 15 million web publishers.
Who operated AddThis?
AddThis was founded in 2004 by Hooman Radfar, Austin Fath, and Dominique Vonarburg. In 2008, it was acquired by Clearspring Technologies, which integrated it into its content sharing platform. In 2012, Clearspring changed its name to AddThis, reflecting the popularity of the product. In 2016, Oracle Corporation acquired AddThis for almost $200 million. Oracle continued to operate the service until May 31, 2023, when all services were terminated, as announced in April 2023.
How did AddThis track users?
AddThis used tracking techniques to identify users and collect their browsing habits. One of the most controversial techniques was canvas fingerprinting, exposed by ProPublica in 2014. This technique creates a unique fingerprint of the user’s device by drawing invisible elements on an HTML5 canvas. This allows the user to be identified and tracked more persistently than with traditional cookies, which can be blocked or deleted. AddThis also used cookies, but canvas fingerprinting was harder to block.
Tracking occurred on websites that used the AddThis widget, such as WhiteHouse.gov and YouPorn.com. YouPorn removed AddThis after the ProPublica article, stating they were unaware of the tracking. AddThis allowed users to opt out of their tracking tools via their corporate website, but the opt-out process required users to provide their name, country of residence, and physical address, which deterred most users.
Why do privacy tools block AddThis?
Privacy tools, such as ad blockers and anti-tracking extensions, block AddThis because it collects browsing data without clear consent and uses invasive techniques like canvas fingerprinting. Even if the user does not interact with the widget, the AddThis script loads and initiates data collection. Moreover, AddThis was a third-party tracking network, meaning it could track users across multiple sites, creating a detailed behavioral profile. This is a violation of user privacy.
By blocking the addthis.com domain, tools prevent the script from loading, thus avoiding data collection. However, it is important to note that DNS-based blocking, such as that of hado99, does not remove ads served from the same address as the content, does not hide the user’s IP, and may break functionality of some applications that rely on AddThis. But for most users, blocking is an effective measure to reduce tracking.
The privacy impact
Oracle shut down AddThis in 2023, but the service’s history serves as a warning about how seemingly harmless tools can collect data extensively. The acquisition by Oracle, a company known for its data activities, also raises concerns about how data collected by AddThis was used or integrated into other Oracle products. Although the service is now defunct, other similar trackers remain active, and awareness of techniques like canvas fingerprinting is essential to protect privacy.
For those seeking a blocking solution, hado99 is a tool that can help block tracking domains, but it is not a complete solution for all privacy issues. It is important to use privacy tools in conjunction with good practices, such as clearing cookies and using privacy-focused browsers.
In summary, AddThis was one of many examples of how online tracking has become common. Blocking these domains is an important step to maintain control over our data.