Feb 13, 2026 · 5 min read
TikTok and X Are Tracking You Across the Web. This Free Tool Shows How.
The Markup's Blacklight privacy inspector now detects tracking pixels from TikTok and X, exposing a surveillance network that spans millions of websites.
The Pixels You Never Agreed To
That shopping site, news outlet, or government portal you just visited may have quietly told TikTok and X everything about your browsing. Not because you logged in. Not because you clicked anything. Because a tiny piece of invisible code was embedded in the page, silently reporting your activity to platforms you may never have signed up for.
The Markup, a nonprofit newsroom focused on technology accountability, just updated its free Blacklight privacy inspector to detect tracking pixels from TikTok and X (formerly Twitter). The tool already detected pixels from Google and Meta, but the two new additions expose how much wider the surveillance network actually reaches.
What Tracking Pixels Actually Do
A tracking pixel is a small piece of code embedded in a website that sends information about your activities back to the platform that operates it. When you visit a page with a TikTok pixel, for example, TikTok receives data about your browsing activity, purchases, and searches, even if you do not have a TikTok account.
When these pixels are spread across thousands of websites, platforms can compile your data into a detailed behavioral profile: your interests, shopping habits, political leanings, and health concerns. This profile is then used to target you with advertising and shape the content you see.
Since 2020, users have run more than 18 million scans with Blacklight, revealing the scale of hidden tracking across the web.
Why TikTok and X Matter Now
TikTok's tracking pixel program has expanded rapidly. The platform's pixel SDK is now embedded across e-commerce sites, media publishers, and government portals. With TikTok's ownership under ongoing scrutiny over data flowing to Chinese parent company ByteDance, the presence of its tracking pixels on third party sites raises additional concerns about where that data ultimately ends up.
X's pixel network, meanwhile, continues to grow. The platform's advertising infrastructure relies on the same cross site tracking techniques used by Meta and Google, building behavioral profiles from your activity on websites that have nothing to do with X itself.
How to Use Blacklight
Using Blacklight is straightforward: enter any URL at themarkup.org/blacklight, and the tool scans the page for tracking technologies. The updated results now show whether TikTok or X pixels are present alongside existing Google and Meta detections.
For deeper analysis, users can download a full archive of detected tracking data, showing exactly what information each pixel collects and where it sends that data. The new features were developed in partnership with computer science students from Brandeis University's Capstone in Software Engineering course.
Real Investigations, Real Impact
Blacklight's pixel detection has already powered major investigations. The Markup previously used the tool to reveal that sensitive personal information was being shared from government benefit websites to Meta and Google through tracking pixels. That finding led to lawsuits and the removal of those pixels from public services.
The pattern extends to healthcare. Kaiser Permanente's tracking pixels leaked 13 million patients' health data to Google for seven years before the practice was discovered and stopped. In France, the CNIL has ruled that email tracking pixels require explicit consent under ePrivacy rules.
Tracking Pixels in Your Inbox
The same technology that tracks you across websites also operates inside your email. Spy pixels embedded in marketing emails work identically, reporting when you open a message, your location, your device type, and how long you spend reading it. Most commercial emails contain at least one tracking pixel, and most email clients load them automatically.
Blacklight covers the web side of this equation. For the tracking that happens inside your Gmail inbox, Gblock detects and blocks spy pixels before they can report your activity to senders. Between the two tools, you can see and stop the tracking pixels that follow you across both the web and your email.