ChatGPT can set a cookie called __obi that stays in a browser for up to a year and gets sent back to OpenAI with conversion and page data when that browser visits advertiser sites running OpenAI’s ad pixel, according to an independent researcher who publishes as Buchodi. The researcher didn’t observe OpenAI linking that off-site activity to specific ChatGPT accounts, a step that would happen on OpenAI’s servers, but the setup works the way a standard third-party ad cookie does. OpenAI classifies __obi as an analytics cookie, and Buchodi found it could still be set for users who allowed analytics cookies but turned down marketing ones. OpenAI told Buchodi it would pass the findings along internally but hasn’t explained publicly why the cookie is labeled analytics.
