OpenAI to implement invisible watermarks for ChatGPT in Europe

OpenAI has announced the implementation of textGrain, an invisible digital watermark for text generated by ChatGPT and Codex. This technology creates a hidden signature that is unnoticeable to humans but readable by machines.

The move is designed to comply with the European Union’s AI Act, specifically Article 50, which mandates transparency regarding AI-generated content. Starting August 2, 2026, new AI models in the EU will be required to indicate the provenance of their outputs so users can distinguish between human and automated content.

Currently, the watermark is available to developers via APIs to help them integrate transparency obligations into their own applications. OpenAI plans to extend this digital signature to cloud-based services and eventually to all ChatGPT and Codex user plans within the European Union.