Claude invisible watermark tags every AI text - but paraphrasing erases it

Anthropic has quietly started sealing an invisible watermark inside every piece of text Claude writes, a move that could make it far harder to pass off AI-generated work as human-made. The Claude invisible watermark now travels silently with anything the chatbot produces, from a quick email reply to a full manuscript, and it survives even after the text is copied and pasted somewhere else.

Key takeaways

• Claude now embeds an invisible, machine-readable watermark inside every text output, applying fully to new models launched from August 2, 2026.
• The mark survives copy-paste but can be erased through paraphrasing, heavy editing, or blending Claude’s text with other writing.
• Coverage spans every Claude app and API, including Claude Cowork and Claude Tag, plus access through AWS, Google Cloud and Microsoft Foundry, regardless of region.
• Older Claude models will receive the watermark during a transition period, but text they already generated stays untraceable.
• Anthropic signed the EU AI Act’s Article 50(2) Code of Practice, effective August 2, 2026, with full compliance required across the market by December 2, 2026.

Anthropic Introduces Invisible Watermarks Across Claude AI Outputs

Anthropic now marks every text Claude generates with a hidden signature that readers cannot spot but detection tools will eventually be able to trace. The company describes it as an imperceptible watermark that doesn’t change what the text says or how it reads, yet quietly rides along with the words wherever they go.

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