Just a couple of weeks after Anthropic announced it would roll out digital watermarks for text generated with its Claude AI tools, the company has introduced a page where you can check files to see if Claude helped make them.
The page, at claude.com/check-content, lets you upload files with a quick spot check and will confirm, “This file shows signs it was processed by Claude,” if it finds content credentials embedded in the file.
But if you’re hoping to prove that someone used Claude for a term paper or want to see if someone’s texts weren’t actually written by the human you’re talking to, you’re going to need to wait. The checker currently works with only a limited number of file types, and none of them are text formats. Instead, the checker accepts multimedia files, including JPEGs, GIFs, MP3s and MOVs — basically image, audio or video files.
A spokesperson for Anthropic told CNET that the tool is specifically to check for Claude’s use through an industry standard called C2PA; a broader AI detection tool is in the works, but not yet available.
“Text checking is via our Detection API (separate tool) and in private preview, and we hope to share more about it in the months ahead,” the spokesperson said. This aligns with a note on the check content tool reads, “To detect watermarks embedded in text we have a Detection API which is currently in private preview to eligible organizations as required under EU law.”
Anthropic has said that its watermarking of text that Claude produces won’t affect the quality, speed or cost of outputs and that these watermarks won’t be visible or affect how text functions or appears. But they will remain with text from Claude even if it’s copied and pasted from one place to another. Anthropic has a sign-up form for businesses or organizations that want to be added to the list for access to the watermark detector.
Anthropic said in its email to CNET that if the C2PA standard expands to include additional file formats, its checker tool will likely adopt them as well.
How does Anthropic’s new checker work?
The free web-based tool has a drag-and-drop option, or you can click to add a file from your device or Google Drive on mobile. According to the website, the file you choose stays on your device or file service, and the checker only reads the file’s credentials, not the file itself.
“Your file is never stored or used for any other purpose,” the page says.
In CNET’s testing of the tool, the detector correctly flagged an image file that was converted in Claude from a PowerPoint presentation. For files that the detector said were not shown to be processed by Claude, a message is shown that reads, “We couldn’t find any signs that this file was processed by Claude. That doesn’t rule it out. Signals like this can be removed when a file is edited, converted, or compressed.”
Omar Gallaga has covered technology, digital culture and other topics for outlets including CNET, NPR, WIRED, Texas Monthly, MSNBC, Consumer Reports, The Washington Post, the Los Angeles Times, The Atlantic and the Austin American-Statesman, where he was a longtime tech reporter, editor and podcaster. He lives in the Texas Hill Country. See full bio
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