Anthropic’s Claude content checker is now live, giving users a way to verify whether a file was created or edited with the company’s Claude AI. The tool arrives just weeks after Anthropic said it would add digital watermarks to text generated by its Claude tools, but there’s a significant restriction on what it can currently scan.
Available at claude.com/check-content, the page lets you upload a file for a quick spot check. If it detects content credentials embedded in the file, it returns the message: “This file shows signs it was processed by Claude.”
What the Checker Can and Cannot Verify
Anyone hoping to confirm whether Claude wrote a term paper or ghostwrote someone’s text messages will have to wait. The checker supports only a limited set of file types, and none of them are text formats. Instead, it accepts multimedia files such as JPEGs, GIFs, MP3s and MOVs, covering images, audio and video.
An Anthropic spokesperson said the tool is designed to detect Claude’s involvement through an industry standard known as C2PA. A broader AI detection tool is in development 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.
That matches a note on the page explaining that text watermark detection runs through a Detection API currently in private preview for eligible organizations, as required under EU law. Anthropic said that if the C2PA standard grows to cover more file formats, its checker will likely add support for them too.
How the Free Web Tool Works
The free, web-based checker offers a drag-and-drop option, or you can click to add a file from your device or from Google Drive on mobile. According to the website, your file stays on your device or file service, and the checker reads only the file’s credentials rather than the file itself. “Your file is never stored or used for any other purpose,” the page states.
In testing, the detector correctly flagged an image file that had been converted in Claude from a PowerPoint presentation. When a file shows no evidence of Claude processing, the tool displays: “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.”
Anthropic has said its text watermarks won’t affect the quality, speed or cost of outputs, and they won’t be visible or change how text functions or appears. The watermarks stay with Claude-generated text even when it is copied and pasted between locations. Businesses and organizations that want access to the watermark detector can sign up through a form provided by the company.
