Anthropic has revealed how Claude will mark AI-generated content — and the approach is more sophisticated than visible labels or metadata tags. Claude will weave imperceptible watermarks directly into generated text, following the EU AI Act's Article 50(2) Code of Practice on transparency of AI-generated content.
How It Works
The watermarking operates at the model level — meaning it's applied directly in the text itself, not as metadata or a separate header. According to Anthropic's support documentation:
Plain text output: Claude weaves an imperceptible watermark directly into the text. Users won't see it, and it doesn't change the meaning, quality, or readability of the response.
Persistence: Because the watermark is part of the text, it travels with the text when copied and pasted elsewhere, and may survive some editing.
