OpenAI adds optional text watermark API feature to meet EU AI Act rules

Key Summary

OpenAI is implementing a text watermark API feature to comply with the EU AI Act's Article 50 requirements, which mandate transparency and machine-readable marking for AI-generated content. The change applies to users in the European Union, with the watermarking feature to be switched on within API project and organization settings. OpenAI has licensed Google DeepMind's SynthID watermark, which will be used in conjunction with C2PA metadata. The text watermarking feature is not a default setting and will be available through the Content Provenance API for eligible use cases. The EU AI Act took effect on August 2, 2026, with a deadline of December 2, 2026 for existing systems to adapt.