AI watermarking

Anthropic announced on August 11 that all future Claude models will embed an invisible watermark in generated text, following Google's lead with SynthID-Text. The move is partly driven by the EU AI Act, which mandates watermarking for AI models released after August 2, 2026, though researchers remain split on whether the technique degrades output quality.

Anthropic is rolling out a watermark verification API that lets approved regulators, media outlets, fact-checkers, and enterprises check whether text was generated by Claude. The system builds on Google's SynthID text method and responds to EU AI Act watermarking requirements in effect since August 2, 2025.

Anthropic published a blog post explaining the mechanics of its planned watermarking system for Claude, which uses Google DeepMind's SynthID-Text approach. The move is required under the EU AI Act's Transparency Code and has triggered user backlash on Reddit and X.