OpenAI will enable automatic watermarking of ChatGPT-generated text by default in the EU to comply with the EU AI Act, while keeping the feature optional in other regions. The proprietary textGrain method embeds detectable patterns in word choices, with detector access limited to selected researchers and organizations.
<p>OpenAI will begin automatically watermarking text generated with ChatGPT in the European Union, the company has announced. It will also offer the watermarking feature in other regions, but it will be off by default outside of the EU.</p>
<p>The move in Europe is driven by a need to comply with the EU AI Act, which took effect in August. It requires marking content produced by AI models in a way that another tool can detect. Unfortunately, there is still no completely effective and reliable way to do that. A few standards already exist, like SynthID and the C2PA project, but they are relatively easy to circumvent for anyone with basic know-how.</p>
<p>The same is likely true for OpenAI's watermark. Its method is proprietary; the company calls it textGrain, and has published a technical paper <a href="https://cdn.openai.com/pdf/e9508624-d767-41b6-a26d-e34ca798ada6/textgrain-entropy-calibrated-watermarking-for-language-model-text.pdf">explaining</a> how it works. But in general, it works like other LLM watermarking tools we've seen in the past: It puts patterns in the word choices that are not clear to a human reader, and that don't meaningfully change the general quality of the output, but that someone with a key can use a specialized detector to find. OpenAI says it will be giving access to the detector to a limited number of researchers and organizations, and providing a request-for-approval process for others to be added over time.</p><p><a href="https://arstechnica.com/ai/2026/10/openai-will-watermark-chatgpt-outputs-by-default-but-only-in-the-eu/">Read full article</a></p>
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# OpenAI will watermark ChatGPT outputs by default—but only in the EU
Source: [https://arstechnica.com/ai/2026/10/openai-will-watermark-chatgpt-outputs-by-default-but-only-in-the-eu/](https://arstechnica.com/ai/2026/10/openai-will-watermark-chatgpt-outputs-by-default-but-only-in-the-eu/)
OpenAI will begin automatically watermarking text generated with ChatGPT in the European Union, the company has announced\. It will also offer the watermarking feature in other regions, but it will be off by default outside of the EU\.
The move in Europe is driven by a need to comply with the EU AI Act, which took effect in August\. It requires marking content produced by AI models in a way that another tool can detect\. Unfortunately, there is still no completely effective and reliable way to do that\. A few standards already exist, like SynthID and the C2PA project, but they are relatively easy to circumvent for anyone with basic know\-how\.
The same is likely true for OpenAI’s watermark\. Its method is proprietary; the company calls it textGrain, and has published a technical paper[explaining](https://cdn.openai.com/pdf/e9508624-d767-41b6-a26d-e34ca798ada6/textgrain-entropy-calibrated-watermarking-for-language-model-text.pdf)how it works\. But in general, it works like other LLM watermarking tools we’ve seen in the past: It puts patterns in the word choices that are not clear to a human reader, and that don’t meaningfully change the general quality of the output, but that someone with a key can use a specialized detector to find\. OpenAI says it will be giving access to the detector to a limited number of researchers and organizations, and providing a request\-for\-approval process for others to be added over time\.
OpenAI is introducing invisible text watermarks called textGrain to ChatGPT and Codex for EU users to comply with the EU AI Act, with opt-in watermarking for API customers worldwide and detector access for approved researchers.
OpenAI announces its compliance approach to the EU AI Act's text provenance requirements, rolling out a phased text watermarking system called textGrain across the API, ChatGPT, and Codex while being transparent about detection limitations, and plans to open source the technology.
Anthropic announced it will watermark text generated by its AI models, including Claude, to comply with the EU AI Act's transparency obligations. The watermark is applied at the model level, persists through copy-paste, and uses C2PA for files.
The EU AI Act mandates watermarking for AI-generated text to ensure detectability within the EU, even for outputs generated outside, with OpenAI planning to comply in future models like Astra.