OpenAI to add invisible watermarks to ChatGPT and Codex text for EU users

OpenAI will start watermarking ChatGPT’s text in the EU

OpenAI will turn on invisible text watermarks for eligible ChatGPT and Codex users on all EU plans in the coming weeks, to comply with the EU AI Act's transparency rules. API developers worldwide can enable watermarking for some models starting today, off by default. The watermark tweaks word choices to leave a detectable pattern that survives copy-paste; the first detectors go only to approved researchers and professional organizations.

Why it matters: In OpenAI's tests, swapping 10% of words dropped detection from about 92% to 66%, so editing text weakens the watermark.