Since 2020, readers have used Blacklight, our pioneering website privacy inspector tool, to run more than 18 million scans. Previously, Blacklight detected tracking pixels from Google and Meta. Today, we’re announcing that it can scan for two more digital trackers: TikTok and X pixels.
A tracking pixel is a small piece of code added to a website that sends information about the site’s users to the platform that operates the pixel. That can include details of a user’s activities, such as their browsing activity, purchases and searches. A website that embeds a pixel often does so to inform its advertising campaigns on the platform that create the pixel. When its pixel is embedded across many websites, the platform can compile a user’s data to build a detailed profile of their interests, behavior and other personal information. These profiles allow other businesses to buy ads from the platform to target categories of users — though this data can also be used for other purposes.
When you look up a website in Blacklight, it will now report if it finds the TikTok pixel or X pixel. More detailed information about the specific data being passed through pixels is also available by clicking on “Learn more” in the top right of the results, then clicking the link to “download an archive.”
To develop these new features, we partnered with a group of computer science students in Brandeis University’s Capstone in Software Engineering course. These students – Yiyou “Felix” Fan, Jiawen “Zena” Hu, Hengye Li, Hongchen “Steven” Yang and Yiquan “Frank” Zhang – researched and developed the features with the support of our product team.
Blacklight’s pixel detection features have already powered our Pixel Hunt investigations, which revealed that sensitive personal user information was being shared from government websites with Meta and Google, leading to lawsuits, removal of pixels from sites and increased government scrutiny. These new features give a fuller picture of the digital privacy landscape by exposing tracking pixels from two more companies.
We hope these new features will help you better understand what happens to your data as you navigate the internet. While Blacklight can’t say exactly what companies like TikTok and X do with our data, it can provide a starting point for deeper investigation into how that data is stored, shared and used across the web.
Do you have questions, suggestions or need help understanding your Blacklight results? You can always reach us at blacklight@themarkup.org.
