You might soon be able to know for sure if something came from a human being or from Claude. Anthropic said this week that text and files generated by its family of AI models will be watermarked to let consumers know. The change will allow the company to comply with EU regulations governing the transparency of AI use.
The EU’s Code of Practice on Transparency of AI-generated Content requires companies that provide and deploy AI systems to inform customers when they are interacting with AI and to include watermarks on AI content. Consumers also must know when they’re exposed to deepfakes and emotion-recognition and biometric-categorization tools.
Watermarking — an authentication process that originated in Italy in the 13th century — is entirely different for AI content. The AI system can automatically embed markers in text indicating that the content originated from AI and not a human. Examples could be different spacing between words and numbers, word sequencing and other invisible signals that remain with the text even if the person copies and pastes it across different platforms. Readers can’t see these markers, but computer systems can.
In its announcement this week, Anthropic said Claude models launched on or after Aug. 2 would include watermarking. That includes content created by Claude through the API, Claude, Claude Code, Claude Cowork and Claude Tag. Watermarking will apply to all Claude-generated content wherever the AI system is offered, not just the EU.
Anthropic said it would share details on detecting the watermarks in the future.
A representative for Anthropic didn’t immediately respond to a request for comment and clarification.
What will be watermarked
Claude will include watermarks in text and files — including .svg, .png, or .jpg — that it generates. With text, the watermarks will be signals embedded into letters and words that will be invisible to readers but visible to machine systems. Even if the text is copied and pasted from text editors such as Windows Notepad or MacOS’s TextEdit, the watermarks will remain. The marks also might not be eliminated through human editing, either.
“Watermarking will be applied at the model level, which means it will be present no matter which Claude product or surface the text comes from,” the company said.
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Image files created by Claude will have signed provenance metadata, including information about where the image came from, who created it and if it has been modified. If someone tries to tamper with it — for example, trying to hide that it was generated by AI — the cryptographic signature will break and thus will show the reader that it was tampered with.
AI transparency is a growing trend. Substack partnered with Pangram to let readers know how much, if any, a post was generated by AI. Suno recently announced changes to help listeners know if a song was created by AI. If LinkedIn customers suspect AI slop, they can let LinkedIn know. Spotify’s new feature, AI Persona, allows listeners and creators to know which music was created with AI.
It’s not foolproof
Anthropic included a caveat in its announcement. The presence of watermarking doesn’t necessarily mean the content or image was created by Claude, nor does the absence of watermarking mean Claude wasn’t involved, either.
For example, let’s say someone wants to repurpose an essay from another writer. They punch the essay into Claude and ask the AI to reword it. The output will have watermarking, but the content’s facts and details came from a writer, not AI. People often use Claude for proofreading, translating and summarizing, the company said.
Someone might also take content from Claude and edit it and combine it with other text. Even if only a small portion of the final draft is from Claude, there could be a watermark, perhaps undermining the legitimacy of the document for the reader.
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Anthropic said content generated or processed by Claude might not have a watermark, for various reasons. It could be that the amount of AI-generated content is too small, or perhaps the content has been “heavily edited, paraphrased, translated or mixed into other writing.”
It’s also possible that a Claude-generated image doesn’t have a watermark either. For example, if someone takes a screenshot of the image and re-saves it as a different file, it won’t have the metadata.
Although Anthropic is trying to comply with EU rules, AI detection has been significantly less than reliable, according to some reports. For example, content from non-native English speakers is often falsely flagged as AI-generated.
