Anthropic staff explains Claude's watermarking mechanism and detection status

HarperSCarroll · x · 2026-08-27

Claude's "invisible" watermark works by shifting the probability of consecutive output tokens, embedding the signal in the chosen words. Consequently, copying and pasting Claude's output retains the watermark, whereas using it for proofreading or minor edits preserves less of the mark. As of now, the technology to detect Claude's watermark has not been publicly released.

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