OpenAI's ad collector links your ChatGPT account to your browsing on 12 sites
ChatGPT now knows what you do on other websites via ad collector
OpenAI's ad collector sets a cookie called __obi on .openai.com, tied to your ChatGPT account. When you visit sites that use OpenAI's measurement pixel, that cookie is sent back, revealing what you browse and buy. The author reproduced the mechanism on a phone, verified with two capture methods, and observed one __obi value sent from 12 commercial websites including Chewy, Wayfair, and HelloFresh. OpenAI classifies __obi as an analytics cookie and did not answer questions about it.
The first row is particularly interesting. The pixel SDK has a code path that omits credentials, and it does not help: the browser attaches cookies to the <script src> request that loads the SDK before any of OpenAI's code runs.