OpenAI's __obi Cookie Connects Browsing to ChatGPT Accounts — SkimNews
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- OpenAI's ad platform at bzr.openai.com issues a JWT (issuer "chatgpt-wadi", audience "bzr.openai.com") that binds a 22-character identifier to the user's account subject, then sets that identifier as the __obi cookie on .openai.com with Max-Age of one year and SameSite=None; Secure to enable cross-site transmission.
- The cookie fires on advertiser pages, with the researcher observing __obi sent to OpenAI from 12 commercial sites under 13 distinct pixel IDs including Chewy, Wayfair, ThriftBooks, Eventbrite, HelloFresh, Coursera, and SeatGeek — every request returned HTTP 202 — and 12 of 30 distinct __obi values reappeared across more than one advertiser in broader traffic spanning 936 pixels over 1,029 hostnames.
- The SDK also scrapes identity from form fields, rendered page text, and the tag-manager data layer (including renamed GTM and Adobe layers); scraped identity outnumbered advertiser-supplied identity 685 events to 255, with postal code the most-harvested form field (100 events across 28 sites).
- Version 0.1.31 of the SDK also collected first/last name and geography before OpenAI narrowed the scope on 27 August; current versions hash email, phone, first and last name with SHA-256 while sending country, region, city, and postal code in plaintext, with a denylist covering passwords, card numbers, SSN, and medical fields.
- Logged-out users are tracked too: 196 of 932 decoded sync tokens carried subject_type "anonymous," with one anonymous identifier per device persisting at least 27 days, and the mechanism does not require a logged-in ChatGPT session — roughly one in five sessions produced a sync token when active.
- OpenAI classifies __obi as an analytics cookie in its public policy — valid one year on chatgpt.com and openai.com — and the sync tokens all carry consent_decision "analytics_allowed," meaning users who accept analytics consent and refuse marketing consent still receive the cookie; OpenAI's press and privacy inboxes acknowledged the researcher's 14 September inquiry without answering either question.
Why it matters: Running a Meta-style third-party tracking pixel on an AI chat product is a structural departure from social-network adtech: ChatGPT users disclose far more sensitive intent than they would on Facebook or Google, and OpenAI's own cookie policy labels the identifier "analytics" while it in fact joins off-site browsing to a logged-in account — a 936-pixel footprint with no public disclosure and no opt-out beyond universal browser controls that only work on Chrome for Android.
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