Users can manage how they are tracked with third-party cookies using a variety of cookie management browser extensions.

For example, Cookie AutoDelete has more than 200,000 users on Google Chrome. Other extensions offer more advanced functionality and are common enough to be covered at Internet how-to sites. Example: The 5 Best Cookie Editor Extensions for Google Chrome

In the future, however, because the Sec-Browsing-Topics header has a Sec- prefix, extensions will not able to filter Topics API data in the same way that users have come to expect for third-party cookies. This would be a step backward in functionality. See discussion at #183.

In order to address concerns about possible future adfraud extensions (are there extensions that modify third-party cookies for adfraud today?) it might be more practical to replace Sec- with a new prefix such as Ad- so that browser extension reviewers could more easily check which extensions might be modifying ad-related data.