Claude's new Scarlet Letter watermark is invisible—for now
Anthropic has introduced an invisible watermarking mechanism into Claude that embeds identifiers within text processed by the model. According to reporting by Ars Technica, the watermark flags all output generated or modified by Claude, including human-written text submitted solely for editing or proofreading. The technical measure aligns with escalating transparency and provenance mandates under regulatory frameworks such as the European Union's AI Act, despite the watermark remaining imperceptible to end users during initial deployment.