Anthropic

Anthropic injects the imperceptible watermark directly into Claude's generated text at the model level, so the watermark is part of the text itself and will be present across any Claude product or surface. Because it is embedded in the text, the watermark can travel when the text is copied and pasted and may persist through some light editing. Anthropic is also working to enable detection tools that will mark positively detected text as having been processed by Claude, though such detections will not be fully conclusive. Answered

We’re implementing watermarking to comply with the EU AI Act. Anthropic, along with several other major AI model providers and around 190 total signatories, signed the EU Code of Practice on Transparency of AI-Generated Content in July 2026. This requires AI system providers to use methods of “marking” AI-generated text. We’re applying watermarking globally at launch because we don't yet have a durable way to scope it by region. However, we will continue to evaluate different approaches, and will share updates when we have them.

Anthropic is embedding imperceptible, model-level watermarks directly into Claude-generated text and says it is working to enable Claude users and third parties to detect those embedded watermarks, with details on detection to come. A positive detection will mark text as being "processed by Claude," but Anthropic cautions that such a result will not be fully conclusive because use of Claude for proofreading or edits does not prove original authorship. Answered

A positive watermark detection indicates the text was processed by Claude and is marked as having been handled by that model. Anthropic cautions that this is not fully conclusive evidence of original authorship or provenance, since someone could have used Claude only to proofread or edit an existing document. Answered