SAN FRANCISCO, Aug. 16 -- Starting this month, every sentence that Claude generates carries a hidden signal. It is not a visible watermark, not a disclaimer appended at the end. The encoding is in the words themselves - specifically, in which words the model chose when alternatives existed.

Anthropic announced on August 14 that it has implemented text watermarking across all Claude models released after August 2, built on a technique Google DeepMind developed and published in Nature in 2024. The immediate driver is Europe. In July, Anthropic signed the EU Code of Practice on AI-Generated Content, which requires AI companies to make their outputs identifiable under the EU AI Act. The watermarking went live globally rather than region by r...