Anthropic to embed invisible watermarks in Claude's text, citing EU law
Anthropic confirmed it will weave imperceptible, machine-readable watermarks into text generated by supported Claude models, to comply with the EU's AI Act transparency rules. Older models will get the feature later; the marks apply everywhere Claude is offered, not just in Europe.
This is the EU's AI transparency code moving from paperwork to product. Anthropic joins roughly 190 signatories to the EU's Code of Practice on Transparency of AI-Generated Content, and the mark will follow Claude's output through copy-paste and some editing, even when work never touches Europe. That last point matters most: a policy written for EU compliance now quietly changes what "Claude wrote this" means for every user, worldwide.
If you use Claude for writing, code comments, or client deliverables, assume the text carries a detectable trace of its origin, even after you've edited it — Anthropic says the mark can survive some editing but not a heavy rewrite or translation.
Engineers: The watermark applies across Claude, Claude Code, the API, Claude Cowork and Claude Tag, and through resellers like AWS, Google Cloud and Microsoft Foundry — so code and text generated via any of these paths could later be flagged as AI-assisted, which is worth knowing before you commit unedited output.
Managers: If your team's output policy assumes AI-drafted work is indistinguishable from human work once lightly edited, that assumption is weakening — plan for detectability when setting disclosure or client-facing AI-use policies.
Do this: Nothing to do yet — Anthropic hasn't published detection details, but note that a heavy rewrite or translation is the most reliable way to remove the mark, and factor that into any workflow where undisclosed AI authorship matters.