Claude Watermark is a browser-based tool for checking text for Claude- and ChatGPT-related artifacts and cleaning the ones it can verify. It focuses on concrete traces such as HTML markup, invisible Unicode characters, non-breaking spaces, and punctuation patterns that can survive copy and paste.
The site also explains Anthropic’s newer statistical watermark for Claude models and is explicit about a key limitation: there is no public detector for that watermark yet. In practice, the product combines a local checker with a paid rewrite flow, so readers can inspect text, remove detectable artifacts, and resample prose when they need to reduce AI-like signals.