# The Decoder — OpenAI will watermark ChatGPT text in the EU but makes it optional for API users worldwide

- Company: The Decoder (the-decoder.com)
- Announced: 2026-10-05T17:32:42+00:00
- Category: capability-change
- Coverage: not counted
- Announcement: yes
- Group: announcements
- Source: https://the-decoder.com/openai-will-watermark-chatgpt-text-in-the-eu-but-makes-it-optional-for-api-users-worldwide/
- Record: https://forck.live/items/16078-openai-will-watermark-chatgpt-text-in-the-eu-but-makes-it-optional-for-api
- Subject: Reporting
- Models affected: ChatGPT, Codex, Astra

OpenAI is adding invisible watermarks to ChatGPT and Codex text in the European Union to comply with the EU AI Act, using a technology called textGrain that embeds a statistical signal in word choices. API watermarking will be opt-in worldwide, unlike Anthropic's mandatory approach. Detection rates vary by text length and content, and editing can reduce detection significantly.

## Evidence

Verbatim from https://the-decoder.com/openai-will-watermark-chatgpt-text-in-the-eu-but-makes-it-optional-for-api-users-worldwide/:

> OpenAI says it will turn on watermarking for ChatGPT and Codex users in the European Union over the coming weeks. API watermarking will be opt-in worldwide, unlike Anthropic's mandatory watermarking for Claude, which applies globally regardless of how users access the models.

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Record: https://forck.live/items/16078-openai-will-watermark-chatgpt-text-in-the-eu-but-makes-it-optional-for-api
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