Tools 2026-08-11

Every sentence Claude writes now carries a hidden mark — and it survives copy-paste

Anthropic has turned on machine-readable marking for Claude's output worldwide, and there is no way to switch it off. Two mechanisms are in play. Generated text gets an imperceptible watermark woven into the words themselves, which stays put when the text is pasted into an email or a document and can survive a degree of editing. Files Claude produces — .svg, .png, .jpg — get signed provenance metadata following the C2PA standard. Every Claude model launched on or after 2 August 2026 supports the marking from day one, and older models are being moved across. It covers the Claude apps, the API, Claude Code, Claude Cowork and Claude Tag, as well as Claude running on AWS, Google Cloud and Microsoft Foundry. Anthropic presents this as meeting its transparency obligations under Article 50 of the EU AI Act, then applies it to every user on the planet rather than just European ones. Its own caveats are blunt: a detected mark means the text may have passed through Claude, not that it definitely did; heavy editing, translation or format conversion can strip the mark; and very short passages may not carry enough signal to read at all.

Why it mattersFor anyone marking homework, this is the closest thing yet to an answer on AI-written work — and the clearest warning not to use it as one. The mark only points one way. Finding it is evidence; not finding it proves nothing, and a student who paraphrases the output or runs it through another language has probably erased it. It also covers exactly one company's models, so the obvious workaround is to use a different chatbot. The broader pattern is worth noting too: a rule written in Brussels for Europe is being shipped to everyone, because running one pipeline is cheaper than running two.

✓ Verified · 4 sources

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Every sentence Claude writes now carries a hidden mark — and it survives copy-paste

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