03 Apr 2024 Search

(this post is subject to change as I come up with more places. Get in touch if you want to suggest one.)

(Update 9 Oct 2025) Happy AB 566 day to all who celebrate.

Now that we have Global Privacy Control for the web, can we do better? Where else do we need it? Not everything is on the web.

The big risk of having GPC for web but no UOOMs for other contexts is that surveillance companies will start forcing or nudging you to interact with them in other ways—if the surveillance options are too easy to use elsewhere, then more companies will use deceptive practices to drive us to all use communications technologies where browser privacy features can’t protect us. From my point of view, as someone who would rather use the web, that would be bad. (Install our app for full product info or to schedule a demo! Press the button on your printer or Internet refrigerator to order! Yikes.)

Smart TVs: As far as I know, these support HTTP, so the existing Sec-GPC header should work fine. (update 9 Oct 2025) Smart TVs are probably the highest-priority device for GPC, because—unlike phones and tablets—a TV stays plugged in all the time, so has enough juice to run an always-on mic and speech-to-text. Yes, finding the right option in the menus is going to be confusing, but GPC could be something that local installers or electronics stores can do as part of an optimization service. A TV buff or their service provider is already going to be digging in to the picture settings to get that frame interpolation setting that Tom Cruise made a video about right.

mobile apps: Same, apps also use HTTP so the same header should work. Set one preference per device or account and have it work across all apps.

other devices with an order button: I don’t know about these, will have to look it up.

email part 1: Email also has headers, so standardizing an opt-out header would also work, but needs to grind through the RFC process.

email part 2: Use the “plus address” or subaddress functionality. CRM systems and related software can already handle RFC 5233-style addresses, so could treat incoming email from bob+sec-gpc@dobbs.example as an opt out for bob@dobbs.example. (Opt-outs in email could be DKIM-signed, too.)

Instant messaging: So many options, should be doable but a pain because all the big companies want to have their own special protocol.

ActivityPub: Normal GPC in a header works if you connect to an instance directly, but a new standard would need to happen to let user opt outs and/or preferences travel with their content. Update 14 Jun 2024: fep-5e53 covers adding opt-out preference signals to ActivityPub.

NFC: The standard behind tap-to-pay and similar features could be extended to support opt-outs. This one would take more coding and have a longer deployment cycle, though.

vehicle license plates: It’s time for a crossover event between the California Privacy Protection Agency (CPPA) and Special Interest License Plates at the DMV. Add a special symbol to license plates to require companies using ALPR systems to treat the plate, and related database records, as opted out. But wait a minute, custom and special-interest plates cost extra! Wouldn’t that be asking people to pay for privacy? (I’d get one, but really just to fly my privacy nerd flag so I don’t count.) Not necessarily—most of these could end up being free to the vehicle owner. In practice, opt out plates would be a way to help resolve privacy class action lawsuits. Instead of getting yet another free credit monitoring service when a company settles a case (and you probably had free credit monitoring from the last class you were in) a company could settle for buying everyone in the class their choice of credit monitoring or a GPC plate. An interesting piece of graphic design work for somebody would be coming up with an easily recognizable symbol that an ALPR system would not get mixed up with any of the other symbols that are allowed on a license plate.

face recognition: Once we have an opt-out symbol for license plates, require companies that process images for the purposes of identifying people to also check for the symbol. Then you could wear it on a T-shirt, on a piece of flair, or on the front of a hat.

(Update 19 Oct 2026): Audio riff. A series of tones to indicate that data and inferences from an event or recording are opted out.

tire pressure monitors: These devices have a unique ID and can be used for surveillance. This probably also apples to a bunch of other little radios that follow you around, but maybe the easier method here is to ban commercial surveillance using little radios that follow people around, since there’s not really a legit use case.

postal addresses: There should be a way to pack an opt out into an apartment number field in an address.

more GPC for web

A GPC-like opt-out for HTML meta tags and X-Robots-Tag HTTP headers: The original GPC for web is a signal from client to server. Adding a header and/or meta tag would make it apply to cases where the personal info is on the server (as in a blog, forum, or profile page) and the recipient of the signal is the client (a crawler or scraper).

robots.txt: Another possible place to put a server-to-crawler OOPS. FIXME: how to handle this to convey permissions—you might want a crawler to check for something like an RSS update, but not harvest your contact info for sale/sharing.

Content Signals: Content Signals is Cloudflare’s implementation of a mechanism for allowing website publishers to declare how automated systems should use their content. is Cloudflare’s implementation of a mechanism for allowing website publishers to declare how automated systems should use their content. Besides the existing ai-train, ai-input, and search options, add a GPC-like option. (More: adding a Content Signals Policy to this site)

In links: Sort of like a nofollow link, you could tag a link containing personal info as opted out: <a class="opt_out" href="mailto:user@example.com">mail me (but don't sell/share my info)</a>. That would send an OOPS for the email address but not any other info collected from the page.

RSS: It might be possible to handle this with the HTTP response header, and not have to put GPC in too many places.

Content licenses: Can a license that allows for re-use of copyrighted material also include opt-out language? notes on Humans Commons

Scraping can already be actionable as a violation of site ToS, but being able to tag a page by or about a person as opted out is another level of protection that imho will help encourage more people to make more useful sites. As a site operator, you want to be able to put up something like a blog, company directory, or event speaker profiles without feeding your site’s people to who knows what.