Free tool · runs in your browser
Hidden character detector
Paste any text to instantly find and remove invisible Unicode — zero-width spaces, bidirectional controls, tag characters, and other carriers used to watermark or fingerprint content. Nothing is uploaded; it all happens in your browser.
What are hidden characters?
Some text carries Unicode codepoints that render as nothing — zero-width spaces, joiners, bidirectional controls, and tag characters. They're invisible to the eye but survive copy-paste, so they can be used to watermark a document, tie a leak back to a source, or fingerprint AI-generated output.
Hidden characters vs. the Claude watermark
Removing hidden characters is necessary but not sufficient for AI-provenance. Claude's watermark is statistical — a bias in the model's word choices (SynthID-Text), not a hidden glyph. This detector clears the invisible-character layer instantly and for free; to break the statistical pattern too, rewrite the text through a different model. Remove the full Claude watermark →
FAQ
What are hidden characters?+
Hidden (invisible) characters are Unicode codepoints that take up no visible space — zero-width spaces (U+200B), zero-width joiners, bidirectional controls, word joiners, soft hyphens, unusual spaces, and tag characters. They can be inserted to watermark, fingerprint, or track a piece of text without changing how it looks.
Is this tool private?+
Yes. The detector runs entirely in your browser using JavaScript. Your text is never uploaded to a server, logged, or stored.
Does removing hidden characters remove the Claude watermark?+
No — not on its own. Claude's watermark (SynthID-Text) is a statistical pattern in the model's word choices, not an invisible character. Stripping hidden characters removes one layer, but to break the statistical watermark you need to rewrite the text through a different model. ClaudeRewrite does both.
Which characters does it detect?+
Zero-width space/joiner/non-joiner, left/right marks and bidi overrides, word joiner and invisible math operators, soft hyphen, byte-order mark, unusual space characters, Unicode tag characters, and noncharacters.