Anthropic announced it will embed invisible watermarks into text generated by new Claude models, including output produced through its API, coding tools and cloud partners. Claude models launched in the EU on or after Aug. 2, 2026, will include machine-readable marking from release, with support planned for older models. The marks will apply worldwide across supported Claude products, including the Claude API, Claude Code, Claude Cowork and Claude Tag, and text generated through AWS, Google Cloud or Microsoft Foundry will also carry the watermark when those platforms use a supported model. The change follows the Aug. 2 start of Article 50’s transparency requirements under the EU AI Act, which require providers of generative AI systems to make synthetic output detectable in a machine-readable format. Anthropic signed the accompanying Code of Practice, as did OpenAI, Google, Meta, Microsoft and Mistral. Text gets a watermark hidden in the words themselves, while supported files such as SVGs, PNGs and JPGs receive a digital signature using the C2PA standard. The file metadata can show that Claude processed an asset and whether the metadata has been altered. Anthropic said the watermark will travel with text when copied and pasted and may persist through some editing. Anthropic has not explained how its text watermark works or shared figures on whether watermarking affects latency or adds to inference costs.