Anthropic· Claude

How Claude’s text watermark works

Announcements How Claude’s text watermark works Aug 12, 2026 Future Claude models will generate text that contains a watermark. This is a way of determining the likelihood that Claude was involved in writing the text, and we, along with several other major AI providers, are implementing this change to comply with the EU AI Act. In this article, we share answers to some of the questions we’ve received about how our chosen watermarking method works, whether it affects Claude’s outputs, and why we’re making this change. To summarize: We use a method of watermarking that does not have any practical impact on the quality or content of Claude’s outputs; The difference between watermarked and un-watermarked text will not be distinguishable to readers; Nothing is added to the text and there are no hidden characters; Watermarking doesn’t require extra tokens, and will not be more expensive; Watermarking carries no identifying information and can’t be traced to a specific person, organization, or chat; Watermarking won’t be specific to Claude. As of August 2, the EU requires AI providers serving its market to mark AI-generated content. …

Around this story

• Ars Technicareported5 days agoClaude's new Scarlet Letter watermark is invisible—for nowreported5 days ago

Also covered byThe Verge,Engadget+28 more30 outlets▾▴

• The VergeAnthropic explains how Claude’s invisible text watermarks will work
• EngadgetAnthropic is watermarking text generated by Claude to comply with EU law - Engadget

Announced

12 Aug 2026 00:00 UTC