Opt-out preference signal
By Gareth HoyleLast updated How we research
An opt-out preference signal is a browser setting or extension that tells every website a person visits not to sell or share their personal information.
An opt-out preference signal is an automatic signal, sent by a browser or extension, that tells businesses a consumer opts out of the sale or sharing of their personal information. The California Privacy Protection Agency says businesses "must honor opt-out preference signals" that meet its requirements and treat them as valid opt-out requests, and names the Global Privacy Control as an example.
California's Opt Me Out Act, AB 566, signed on October 8, 2025, goes further. From January 1, 2027 it requires browsers to let California consumers send the signal, according to Hunton Andrews Kurth.
Why do opt-out signals matter to a data seller?
Opt-out signals matter because a consumer who opted out of sale cannot have their personal information included in a later license that is a CCPA sale. Your records need to show who opted out and when, so those people can be excluded before a sample is drawn.
Is this the same as an AI training opt-out?
It is not. Opt-out preference signals come from consumers under privacy law. AI training opt-outs come from site owners and rights holders, through robots.txt rules or an EU text and data mining reservation.