ChatGPT is now tracking your web browsing

OpenAI is now tracking what you do on third-party websites and connecting that activity directly to your ChatGPT account.

According to a technical analysis of OpenAI's ad infrastructure, ChatGPT sets a cross-site cookie called __obi. When you visit commercial sites like Chewy, Wayfair, or HelloFresh that run OpenAI's ad tracking code, your browser sends that cookie to bzr.openai.com. The payload includes your browsing history, searches, and scraped form data like hashed emails and unencrypted postal codes.

Why it matters: Most ad networks build probabilistic profiles, but OpenAI links this cross-site data directly to your specific ChatGPT user ID. The system also tracks logged-out users via a persistent device identifier, and OpenAI classifies __obi as an "analytics" cookie, meaning it collects your data even if you opt out of marketing cookies.

Know this: You can stop __obi from sending your browsing data by blocking third-party cookies or adding bzr.openai.com to your content blocker.

Turns out your prompt history isn't the only thing OpenAI is reading.