Anthropic has said it will embed watermarks in text and files generated by future Claude models released in the EU, as part of efforts to comply with the bloc's AI Act transparency rules. The company also plans to retrofit watermarking to already-released models during the transition period allowed under EU law, with marking applied globally wherever Claude is offered rather than only within Europe.

According to a help document published on Monday, generated text will carry an imperceptible embedded watermark that persists through copying and some editing, while generated files will include digitally signed provenance metadata using the C2PA standard where supported. The scheme covers the Claude Platform (API), Claude, Claude Code, Claude Cowork and Claude Tag, including third-party hosts such as AWS, Google Cloud and Microsoft Foundry. Anthropic has acknowledged limitations, noting detected watermarks aren't conclusive proof of AI authorship and their absence doesn't rule out AI involvement, while critics point out that image watermarking has already been defeated and that removal tools exist for C2PA metadata.