OpenAI plans to introduce invisible text watermarks for eligible ChatGPT and Codex users in the European Union, TechCrunch reported on October 5, citing a company announcement. The rollout is scheduled over the coming weeks across all plans, rather than becoming a global default at launch.

According to the report, developers worldwide can also enable watermarking for selected API models, with the feature switched off by default. That makes the consumer rollout and developer controls distinct: an EU product policy does not mean every OpenAI API response will automatically carry the signal.

A pattern in generated words

The method, called textGrain, subtly changes word-selection patterns so a detector can recognize a statistical signal. Because the pattern is embedded in the wording, it can travel with copied text without requiring a visible label. TechCrunch reports that OpenAI says the watermark does not identify individual users.

Detection is not universal. Editing, translation and short passages can weaken the signal. OpenAI’s developer documentation confirms that text verification currently requires approval, including for research and academic organizations, rather than offering unrestricted public access.

Transparency, not proof of authorship

The European Commission says the AI Act’s Article 50 transparency obligations have applied since August 2, 2026, including machine-readable marking of AI-generated or manipulated content.

For publishers and developers, the important distinction is between detecting a supported provenance signal and establishing authorship. OpenAI’s documentation explicitly cautions that an absent signal does not prove content is human-created. Watermarking adds evidence for review; it does not settle how much human editing or judgment shaped a passage.