- OpenAI plans to implement invisible ‘textGrain’ watermarks for suitable ChatGPT and Codex outputs in the EU.
- The introduction of this system means that machines will be able to differentiate AI-generated text in accordance with the requirements of the EU AI Act.
- OpenAI advises that rephrased texts or translated outputs may lessen the probability of detecting the watermark.
OpenAI has announced that the company will integrate invisible watermarks into the outputs from ChatGPT and Codex in the European Union. The measure will enable OpenAI to comply with the new requirements of the EU AI Act regarding transparency.
These marks will not be visible as they are not explicit marks on the text. The company is going to manipulate the way the use of words in the model so that machines are able to recognize the created patterns.
OpenAI Introduces textGrain for AI-Generated Text
OpenAI calls its new text watermarking system textGrain. The technology works by slightly changing the statistical pattern behind the choice of words and word pieces of the model.
The readers will not notice the modification during reading. The technology introduces no extra symbols, spaces, etc. Therefore, the watermark blends into the texts. A detector can then look for that pattern and assess whether OpenAI technology generated the content.
OpenAI says it will begin adding the watermark to eligible ChatGPT and Codex output in the EU over the coming weeks. The rollout will cover users across ChatGPT plans in the region. The company will not make text watermarking a global default at launch. However, API customers worldwide can opt into the feature for selected models.
Further, OpenAI mentions the watermark has little effect on model speed. Its testing also found no meaningful change in model performance. The company states that this technology aims at making an additional way to recognize AI-generated texts.
The system is different from traditional AI detectors. Those tools usually examine writing patterns after someone generates the text. textGrain embeds a statistical signal during generation itself. OpenAI says this approach gives it more control over the balance between detection and response quality. The company also plans to release textGrain as open-source technology.
EU AI Act Pushes AI Providers Toward Machine-Readable Marks
The change comes as transparency rules under the EU AI Act take effect. Article 50 requires providers of certain AI systems to mark AI-generated or manipulated content in a machine-readable format.
The European Commission believes these marks should allow other systems to detect AI-generated content. These regulations are meant to limit the impact of deception through synthetic media. The transparency requirements came into force on August 2, 2026. They refer to text, video, audio, and image systems produced in certain conditions.
Nonetheless, not every AI generation is included in the scope of these regulations. The European Commission states that some exceptions exist, including some short outputs and code. The EU has also proposed a Code of Practice aimed at helping the AI industry in fulfilling the requirements. The code focuses on marking and detecting AI-generated content.
The European Commission says the marking methods should work in a machine-readable way. Other AI providers are also preparing similar measures under the EU’s transparency rules, including Anthropic adding hidden watermarks to Claude AI text under EU rules.
They should also remain effective and reliable as far as technology allows. Therefore, the textGrain system of OpenAI forms part of a wider effort to improve AI content provenance.
Watermark Detection Will Initially Remain Restricted
OpenAI will not immediately release its text watermark detector to everyone. Instead, approved researchers and expert organizations can apply for access. The company says the restricted approach will help researchers test the system and improve its reliability. OpenAI also wants to study how well the watermark performs in real-world situations.
The detection system will indicate whether the text has OpenAI watermark or not. According to OpenAI, the system does not identify the user and will not disclose the prompts and discussions of users. OpenAI has also acknowledged the limitations of their system. The watermark will be harder to detect after significant rewriting of the text.
Translation brings some challenges as well. Changing a text to another language may weaken the statistical signal, thus making detections less accurate.
Short texts present issues too since they do not give enough input of words for the detector to process. OpenAI says its watermarking approach works better when a passage gives the system enough text to analyze.
The current information from the company also shows that detection rates vary across languages. Its testing found different results among the official languages of the EU. This implies that even after detecting the watermark, it should not be considered as the ultimate evidence of the authorship of a text.
OpenAI points out that although its signal can indicate the provenance of a text, it does not serve as a proof of authorship per se nor does it show what exactly that particular person did.
Watermarks Will Not Replace Other AI Disclosures
According to OpenAI, text watermarking will aid in supporting the EU AI Act, but it will not serve as a substitute for other forms of disclosures. The organization distinguishes between machines recognizing the origins of the material, as opposed to humans, and visible indications. The function of a watermark is to provide an indication to the machine, while the function of the label is to inform the person of a change or generation via an AI tool.
The European Commission also steps in regarding this difference. Its instructions indicate that the machine-readable mark does not eliminate the requirement for some other required disclosures from users or implementers.
Thus, these changes may affect the way some companies will operate ChatGPT and Codex in the EU. Those organizations that are utilizing AI-generated texts have to evaluate how the new mark can be incorporated into their working processes.
At the same time, OpenAI has announced that the introduction will be gradual rather than launching the system at once across the globe. The company says this approach will allow it to collect feedback and assess the technology. For now, the EU will become the first major region where eligible ChatGPT and Codex text receive the invisible text watermark of OpenAI by default.
The move marks a new step forward in the journey to make it easier for machines to recognize AI-produced materials. However, OpenAI’s alerts indicate that the watermarking process has its own drawbacks, especially when it comes to rewriting, translations, or short sentences.
