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1 / 3Anthropic extends its text watermark to older Claude models, with no opt-out×

The change

Anthropic's invisible text watermark now covers Mythos 5, Opus 4.7, Opus 4.6 and Sonnet 4.6, The Independent reports, in response to EU rules. It applies to all users worldwide.

Who can see it

Only eligible groups such as regulators, journalists and researchers can detect it, so ordinary users cannot check their own text.

The limits

Changing API sampling settings reportedly strips it on Opus 4.6 and Sonnet 4.6, and Anthropic concedes short texts may not carry enough signal.

Sources and the full story

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Anthropic extends its text watermark to older Claude models, with no opt-out

Anthropic's invisible text watermark now covers Mythos 5, Opus 4.7, Opus 4.6 and Sonnet 4.6, The Independent reports, in response to EU rules. It applies to all users worldwide. Only eligible groups such as regulators, journalists and researchers can detect it, so ordinary users cannot check their own text. Changing API sampling settings reportedly strips it on Opus 4.6 and Sonnet 4.6, and Anthropic concedes short texts may not carry enough signal. SourcesB

Sources

• BAnthropic's Claude will now leave a trail (The Independent via Yahoo)uk.finance.yahoo.com

This story ran in the Morning Brief of November 4th 2026.