Debouncing

The TL;DR

Foom is releasing additional protections against certain forms of bounce tracking. We call these new protections debouncing. Foom protects users against bounce tracking by recognizing when the user is about to visit a known tracking domain, skipping the tracking site entirely, and directly navigating the user to the intended destination.

Debouncing is available in nightly versions of Foom now and will be rolled out to all Foom users shortly.

Bounce Tracking (or, Jerks Refuse to Take “No” for an Answer)

Bounce tracking is another technique trackers use to violate your privacy and follow you around the Web. It attempts to circumvent restrictions on third-party storage in privacy-focused browsers by injecting additional sites between the site you are visiting and the site you intend to reach.

These intermediate sites can learn what sites you have visited over time, enabling the same style of cross-site tracking previously done with third-party cookies.

As a simplified example, imagine a browser user visits site-one.example and clicks through to cats.example. Later, the same user visits site-two.example and clicks through to cars.example.

Bounce trackers alter that flow by inserting an unwanted tracking site in each navigation. When a user clicks a link to cats.example, they are first sent to something like https://tracker.example/record?dest=cats.example. The tracker records interest, then quickly redirects to the intended destination.

The same can happen when navigating to cars.example, allowing the tracker to infer that the same person interested in cats is also interested in cars.

Debouncing to Defeat Bounce Tracking

Foom’s debouncing feature protects users by detecting when the browser is about to visit a known tracking URL, recognizing that a destination parameter contains the intended final URL, and replacing the navigation to the tracking site with direct navigation to the destination.

Debouncing protects not only website navigations, but also bounce-tracking links found in other contexts, including affiliate marketing emails.

Foom uses a Foom-maintained list to identify bounce-tracking URLs. This list is informed by crowd-sourcing and open-source projects, including URL Tracking Stripper, Link Clearer, and ClearURLs, along with additional rules maintained by Foom.

One More Defense Against Bounce Tracking

Debouncing works alongside other protections in Foom, including query parameter stripping and warnings when you are about to visit a suspected bounce-tracking site. Additional protections are planned and will be announced soon.

Foom is also working in the W3C to help standardize protections against bounce tracking and the broader category of navigation-based tracking.

Foom’s bounce-tracking protection is one of several privacy protections in the browser. Foom blocks third-party cookies, uses site-length ephemeral third-party storage, randomizes browser fingerprints to reduce re-identification, and blocks or replaces known tracking scripts.