Claude Watermark is an open-source tool designed to detect and strip away the invisible structural traces left behind by AI chat interfaces. When text is copied from these chat platforms, it frequently contains hidden artifacts such as zero-width characters, exotic spaces, hidden HTML class names, and distinct typography choices. Claude Watermark exposes these elements by showing their exact count and position, relying on concrete byte-level data rather than statistical probability scores.

Built on an MIT open-source engine, the tool operates entirely within your browser, which guarantees that none of your pasted text is ever uploaded or processed on external servers. It is fully free, offers unlimited cleanings, and requires no registration or user account. Users can instantly scrub their text of all detected artifacts using a simple one-click cleaning feature.

Please note that Claude Watermark is designed specifically to target technical and structural byte-level traces. It does not claim to detect Anthropic's internal statistical watermark, as that remains verifiable only by Anthropic itself.

Pros of Claude Watermark

Completely free to use with unlimited runs and no account registration required
Runs locally in your web browser, ensuring complete privacy with no data uploads
Uses exact byte-level verification to show the precise count and position of hidden HTML, zero-width characters, and exotic spaces
Enables one-click cleaning to easily strip all detected traces from your text
Fully transparent and open source under the MIT license

Cons of Claude Watermark

Cannot detect Anthropic's proprietary statistical watermark
Limited to removing structural byte-level artifacts rather than altering the stylistic or semantic flow of AI-generated writing

Frequently Asked Questions

What exactly does Claude Watermark detect?

Claude Watermark scans your pasted text for hidden structural artifacts left behind by AI chat interfaces. This includes hidden HTML class names, zero-width characters, exotic spaces, and unexpected typography formatting. It reports these findings with exact counts and positions based on actual bytes.

Is my pasted text secure and private?

Yes, completely. Claude Watermark runs entirely in your local browser window. Absolutely nothing is uploaded to external servers, protecting your privacy.

Can it bypass Anthropic's statistical watermark?

No. The tool does not detect or remove Anthropic's statistical watermark, as nobody outside of Anthropic has the ability to detect it. Instead, it focuses on cleaning up the physical byte-level formatting remnants left behind by the chat interface itself.

How do I clean my text using this tool?

Simply paste your text into the interface to see the detected traces. You can then remove all identified hidden elements with a single click, leaving you with clean text.