Anthropic Adds Invisible Watermarks to Claude Outputs to Meet EU Rules

Anthropic says Claude will generate text with an invisible, key-based watermark to satisfy EU AI transparency rules. The pattern, which can be decoded with a key (illustrated using digits of pi), is designed to not affect output quality or cost and is inspired by Google DeepMind’s SynthID-Text. An API will provide decoding keys to verify AI involvement. Limitations include not being able to tell if Claude wrote or simply edited text, potential detection issues for translations or very short passages, and less watermarking in code. Watermarks will be added to all Claude outputs from post-August 2 models, with older models updated later; images will carry a cryptographic metadata note as well."