Anthropic will start embedding invisible watermarks in text and images generated by Claude

Anthropic has revealed that Claude will quietly embed invisible watermarks into AI generated text, with the markers potentially remaining even when the text is copied and pasted elsewhere. The company will also add digitally signed provenance metadata to supported image files using the C2PA standard, as part of its compliance with new transparency requirements under the EU AI Act that took effect on August 2.

The markers will be applied at the model level across Claude products and interfaces, including Claude, Claude Code, Claude Cowork, Claude Tag, the Claude Platform API, and third party services such as AWS, Google Cloud, and Microsoft Foundry. New Claude models will include the system from launch, while Anthropic is still working to add it to existing models. The rollout will be global rather than limited to the European Union.

Anthropic is also developing tools and technical documentation so users and third parties can detect the markers. It's also worth noting that a detected marker only indicates that Claude may have processed the content, not that it originally wrote it. This could apply even if the user only used Claude for minor tasks like correcting grammar or translating text. However, the system is not definitive, since C2PA metadata can be removed, while heavy editing, paraphrasing, translation, or short passages may make text watermarks harder to detect.