OpenAI rolls out invisible textGrain watermarks for ChatGPT and Codex under EU AI Act

OpenAI announced on October 5, 2026, that ChatGPT and Codex will embed invisible watermarks called textGrain into text outputs for EU users. This initiative ensures compliance with the EU AI Act, specifically Article 50 of Regulation (EU) 2024/1689, which became effective August 2, 2026. The law requires providers of synthetic content to ensure outputs are machine-readable and detectable as artificially generated. Deployers must also disclose AI-generated text regarding public interest matters, unless human editorial control is applied.