ChatGPT now knows what you do on other websites via ad collector

TL;DR Highlight

OpenAI's ad pixel sets an __obi cookie that links activity on other sites to your ChatGPT account

Who Should Read

Web or backend developers who embed ad/conversion pixels on their sites or are evaluating ChatGPT ads

Core Mechanics

__obi cookie is tied to your account
- ChatGPT generates 16 random bytes and puts them in a 60-second signed token (JWT) alongside the account.
- bzr.openai.com then sets it as a .openai.com cookie lasting one year.
The cookie flows out via advertiser sites
- Advertisers install OpenAI code on their sites, which sends __obi to OpenAI along with page data.
- The author says this includes products searched, articles read and purchase behavior.
Just loading the script leaks it
- The SDK has a no-credentials path, but it doesn't help.
- The browser attaches cookies to the request that loads the SDK script (oaiq.min.js).
It scrapes identity from forms and pages
- In observed traffic, scraped identity events numbered 685 versus 255 supplied by advertisers.
- Email, phone and names are SHA-256 hashed, while country, region, city and postal code go in the clear.

Community Reactions

Browser protection info was shared
- Commenters said Firefox, Brave and Safari block this while Chrome and Edge do not.
- Another said strict cookie partitioning stops the link between your account and ad views.
Users reported DNS blocking
- One commenter's DNS server with Hagezi blocklists returns NXDOMAIN for bzr.openai.com.
- Others suggested uBlock Origin plus Privacy Badger.
Many said the tech is old but the context is different
- Some noted it's the same standard adtech Facebook has used.
- Others found it worse because people share more private things with chatbots and pay for subscriptions.
Spread of ChatGPT trackers was noted
- One comment cited Bloomberry data saying sites with ChatGPT ad trackers are on track to double from last month.
- Another linked an AdExchanger report saying this has existed since April.

How to Apply

Check for __obi in the network tab
- Today, open DevTools on an advertiser site and filter requests to bzrcdn.openai.com and bzr.openai.com.
- Check whether the request headers carry the __obi cookie.
Audit third-party pixels on your site
- Search your tag manager for the OpenAI pixel (oaiq) and check the automatic matching setting in Ads Manager.
- Turn off automatic identity collection if you don't need it.
Exclude the pixel from sensitive paths
- Don't load the pixel on pages like medical, lending or legal intake whose URL path alone reveals sensitive info.
- The article says origin plus path is sent and such paths were collected.
Update consent wording and cookie policy
- Classify the OpenAI pixel as marketing, not analytics, in your consent banner.
- Tell visitors their activity may be linkable to a ChatGPT account.

Try It

copy & run

# Paste in the browser console (F12): a quick check for whether the page loaded the OpenAI pixel

performance.getEntriesByType('resource').map(r => r.name).filter(n => /openai\.com/.test(n)).forEach(n => console.log(n));

// If bzrcdn.openai.com/sdk/oaiq.min.js or bzr.openai.com/v1/sdk/events appears, the pixel loaded.

// Next: in the Network tab, check whether the Cookie header on those requests has __obi. (It is HttpOnly, so document.cookie won't show it)

Terminology

Third-party cookieA cookie set by a domain other than the site you're visiting. It acts like a name tag that follows you across sites.

SameSite=NoneA setting that sends the cookie even on cross-site requests. The article says __obi is the only OpenAI identifier configured this way.

JWTA short signed ID card issued by a server. Here it binds account and identifier and is valid for 60 seconds.

Cookie partitioningGiving each site its own separate third-party cookie storage. The same cookie ends up in a different drawer per site.

Conversion pixelA small tracking snippet that reports whether someone who saw an ad later took an action like buying.