AliExpress's website executes inaudible audio in your browser to create a unique "fingerprint" of your device and track your activity without relying on traditional cookies. The technique leverages the Web Audio API to generate a signal and measure minute variations specific to your hardware—variations influenced by your processor, operating system, browser, and drivers.
The discovery came to light when a developer noticed his multi-point Bluetooth headphones were failing to switch properly between his computer and phone whenever an AliExpress tab remained open. The silent audio appeared to be interfering with the Bluetooth connection, making the issue impossible to ignore.
Some browsers already block this tracking method by default. Brave prevents it automatically, while users of Chrome, Firefox, and other browsers can install uBlock Origin to stop the technique. This approach represents a growing category of fingerprinting methods that circumvent cookie-based tracking by exploiting device hardware characteristics instead.