Closed labs can watermark outputs because they control the endpoint.
Open weights have no such control. That’s why our research embeds fingerprints directly into the model. It is designed to survive fine-tuning, merging, and distillation.
The mark belongs in the weights, not the output.
Anthropic says new Claude models will embed invisible watermarks in all generated text, everywhere Claude is offered.
The watermark is part of the text, it isn't metadata: "it will travel with the text when it's copied and pasted elsewhere, and may persist through some editing."
This starts with models launched on or after August 2, 2026, under an EU AI Act code Anthropic signed. Anthropic is still working on adding it to current models. The rollout is worldwide.