Anthropic watermarks all Claude outputs globally with marks that “may persist through some editing”

Anthropic has signed the EU AI Act Code of Practice on transparency for AI-generated content. Starting in August 2026, new Claude models will embed watermarks in text and attach signed provenance metadata to files.

Claude models that launch in the EU on or after August 2, 2026, will ship with this labeling baked in. The requirement won’t stop at EU borders either. It’ll apply globally across all Claude products, including the API, Claude, Claude Code, Claude Cowork, and Claude Tag. Generated text will carry embedded watermarks, while generated files will get digitally signed provenance metadata. Existing models get a transition period under the law, but Anthropic says it’s already working on retrofitting them.Ad The company also plans to release verification tools so users and third parties can check the labels, though it hasn’t said when. Developers that integrate Claude into their products must determine which Article 50 requirements apply to their services, according to Anthropic.AdDEC_D_Incontent-1 Anthropic plans to use two types of labels. Text generated by Claude will carry an invisible watermark that doesn’t affect its meaning, quality, or readability, according to the company. The watermark survives copying and pasting and “may persist through some editing.” It gets applied at the model level, so it doesn’t matter which Claude product you’re using. Supported files, including .svg, .png, and .jpg images, will carry signed provenance metadata based on the open C2PA standard, developed by the Coalition for Content Provenance and Authenticity. The signature indicates that Claude processed the file and can reveal later tampering. Text watermarks should also work through cloud partners such as AWS, Google Cloud, and Microsoft Foundry, though those platforms may not support signed metadata.Ad Anthropic is upfront about the limits. A detected watermark doesn’t mean Claude actually wrote the content. People use Claude all the time for proofreading, translating, or summarizing, so the output might carry a watermark even though the ideas came from a human. No watermark doesn’t clear things up either. The model might have shipped before watermarking rolled out, the text could have been heavily edited or translated, the passage might be too short for reliable detection, or the metadata got stripped through format conversion or a screenshot.AdDEC_D_Incontent-2 The real test is how well these watermarks survive editing, reformatting, and translation.