Anthropic Adds Invisible Watermark to Claude Text to Curb Undetected AI Writing

Anthropic will embed an imperceptible watermark in Claude-generated text to improve transparency and help verify AI authorship under the EU AI Act. The mark travels with copied content, may persist through some edits, and Anthropic plans to extend it to older models; third parties will receive detection tools. While promising for publishers and educators, heavy editing or mixing with other writing can defeat the watermark, and it does not prove original authorship. Google DeepMind has a similar SynthID approach for AI-generated content.