Brave Browser Catches AliExpress Using Audio Fingerprinting to Track Users

This technique is known as audio fingerprinting, and it’s part of a broader category called browser or device fingerprinting.

How Audio Fingerprinting Works

Unlike traditional tracking methods that rely on cookies stored in your browser, fingerprinting works by collecting small technical details about your device and combining them into a unique identifier. Audio fingerprinting specifically works like this:

• A website plays an inaudible or near-silent audio signal through the device’s speaker or audio stack.

• The device’s audio hardware processes that signal in a way that’s subtly different from every other device, due to manufacturing variances, drivers, and system configuration.

• The website measures how the output differs from the original signal.

• That measurement becomes a persistent identifier tied to your specific device.

Because this doesn’t rely on cookies, clearing your browser history, using incognito mode, or even switching accounts doesn’t stop it. The fingerprint stays the same as long as you’re using the same device.

Why This Matters

Fingerprinting techniques like this exist specifically to get around the privacy protections users think they have. Most people assume that clearing cookies or browsing privately means they’re no longer being tracked. Audio fingerprinting — along with other methods like canvas fingerprinting or font enumeration — proves that assumption wrong.

For a platform as large as AliExpress, this kind of tracking can be used to build detailed profiles of shopping behavior across sessions, devices, and even after users have explicitly tried to protect their privacy. It also raises broader questions about how many other major platforms may be using similar undisclosed techniques.

How Brave Stops This

Brave includes built-in fingerprinting protections that are active by default — no extensions or manual configuration required. The browser detects and blocks common fingerprinting techniques, including audio-based methods, by randomizing or restricting the data these scripts can collect.

This is part of why privacy-focused browsers have grown in relevance: as tracking methods get more creative, protection increasingly needs to happen at the browser level rather than relying on users to manage settings themselves.

What You Can Do

If you’re concerned about fingerprinting on sites you use regularly:

• Use a browser with built-in fingerprinting protection, such as Brave.

• Keep your browser and OS updated, since some protections improve with each release.

• Be aware that private/incognito mode does not protect against device fingerprinting — it only clears cookies and local history.

As we covered in our previous analysis of browser tracking techniques, no single tool eliminates all forms of tracking, but stacking the right protections significantly reduces your exposure.

The Bigger Picture

This incident is a reminder that tracking technology continues to evolve faster than most users realize. As cookies become less effective for tracking due to regulation and browser restrictions, companies are increasingly turning to fingerprinting methods that are harder to detect and block.

Whether AliExpress intended this as a deliberate anti-fraud measure or a tracking mechanism, the lack of transparency is the core issue. Users deserve to know when and how their devices are being profiled.

What do you think — should companies be required to disclose fingerprinting techniques the same way they disclose cookie usage? Stay tuned on HAKKTECH for updates as this story develops.