Ad targeting uses browsing and profile data, such as interests, purchases and websites visited, to select personalized advertising. It can involve the sale and sharing of personal data between advertising companies and brokers. Two complementary measures can help: a browser privacy signal and advertising opt-out tools that communicate your preferences to participating businesses. Neither removes every existing profile, but both can reduce some uses of your information.
Send a privacy signal from your browser
Global Privacy Control
Global Privacy Control (GPC) communicates a preference to opt out of certain sales or sharing of personal information. Supporting browsers and extensions can send the Sec-GPC: 1 header and expose the preference through a JavaScript signal. Its legal effect depends on the applicable jurisdiction, including requirements in some US states. It is not a universal guarantee that all tracking will stop.
In practice:
- Check whether your browser, such as Brave, DuckDuckGo Browser or Firefox, offers a GPC setting, and enable it where available.
- If it does not, consult the official GPC implementation list for supported software before installing an extension.
- Once enabled, the browser sends the signal automatically. Continue to review cookie consent choices where relevant, particularly for non-essential advertising cookies.
The signal helps express your preference consistently. What a particular company must do with it depends on the law that applies and the processing involved.
Do Not Track has limited practical effect
Do Not Track (DNT) is an older browser signal associated with the DNT: 1 header. Many sites have not honored it, and it should not be treated as an effective tracking blocker or a broadly enforceable European opt-out. Browser support also varies. GPC and concrete browser privacy protections are more useful starting points than relying on DNT alone.
Use advertising preference tools where available
In addition to a browser signal, some platforms let you manage several advertising preferences in one place. These tools can reduce the need to visit participating advertising businesses individually, but the participants, available choices and persistence of those choices differ between services.
TrustArc Preference Manager
The TrustArc Preference Manager is one place to review privacy or advertising choices supported by its participating services. Read the options shown carefully: an advertising opt-out, a sale or sharing opt-out and a deletion request are different actions. Do not assume that a preference tool removes your records from every partner's database.
What to do:
- Open the preference manager.
- Review the choices offered and the companies or services they cover.
- Save your preferences and follow any confirmation instructions.
Some opt-outs depend on browser storage or apply only to that browser or device. Check the tool's explanation before clearing cookies or switching devices.
This does not cover every broker or people-search website. For those, you may need a direct opt-out form or an eligible GDPR erasure request, after identifying where your information appears through a personal data audit.
Practical steps to combine
- Enable GPC using a supported browser or extension to express your sale and sharing preference consistently.
- Review a centralized preference tool where it covers services relevant to you. Check its scope instead of assuming it reaches every advertiser.
- Reject non-essential cookies through the site's consent controls where appropriate. Browser signals and preference tools do not replace every consent decision.
- Address existing broker and directory records directly. GPC and advertising opt-outs do not necessarily remove profiles from people-search sites, Pages Blanches and Pages Jaunes, or marketing databases.
A free scan shows the records Data Knight detects across supported sources. You can then choose what to request removal of and authorize us to send eligible requests on your behalf. For the wider picture, read what a digital footprint is and our digital footprint and GDPR removal guide.
Want to know which supported brokers and websites expose your information? Start a free digital footprint scan. Review your report, then choose what to request removal of.
Read next: Utiq: disable operator-based tracking · Who buys personal data? · Personal data rights explained · Article 17 GDPR: erasure rights
