17 August 2026

Anthropic adds invisible watermarks to Claude text for EU compliance

Anthropic, the company behind the Claude chatbot, is adding invisible watermarks to text Claude generates to comply with EU AI Act rules requiring AI-generated content to be identifiable.
The watermarks work by using low-stakes word choices (like 'overcast' versus 'grey') to embed an undetectable pattern readers cannot see but detection tools with the right key can find.
Anthropic says watermarking will not change Claude's speed, cost, or output quality, and a watermarked response looks identical to an unwatermarked one to readers.
Complete rewrites will remove watermarks, but light editing will not, and watermarking has minimal effect on code since the model has fewer valid word choices when writing functional code.
Google's Gemini chatbot already uses the same SynthID-Text watermarking approach since 2024, and other major AI developers will implement their own watermarks under the same EU requirements.