OpenAI Unveils New AI Text Watermarking System Coming to ChatGPT, Codex, and the API

OpenAI says it’s rolling out a new, EU-driven text watermarking system meant to satisfy requirements under the EU AI Act. The company introduced textGrain, which embeds an invisible statistical signal into generated text and uses a detector to look for that pattern. OpenAI plans to start watermarking eligible ChatGPT and Codex outputs in the European Union over the coming weeks for all subscription plans available there, but it won’t make watermarking a global default at launch. For developers using the API, watermarking is opt-in immediately, enabled for select models and off by default worldwide.