Sourcing note: this item rests on a single reporting chain, 404 Media's own test advertising campaigns. Other coverage, including Gizmodo, reports those tests rather than running independent ones. This item will be updated when OpenAI or another outlet independently confirms or disputes the findings.
404 Media ran its own campaigns and found that advertisers can upload raw or hashed email addresses, phone numbers, or Android advertising IDs, which OpenAI matches to ChatGPT accounts. Lists need at least 25,000 matched users for inclusion targeting, with smaller lists usable for exclusion. A separate control, called context hints, lets advertisers describe the conversations where an ad should appear, and turning off ads personalization does not stop targeting based on the current chat, according to the settings text 404 Media cited. OpenAI says uploaded files are deleted after processing, usually within 24 hours, and that advertisers do not see which individuals matched. The ads run on the Free and Go tiers.