Claude Watermark Detector
Check any AI-generated text for Claude's invisible watermark characters — see what's hiding in it, for free, right in your browser.
What This Claude Watermark Detector Finds
Claude's SynthID-Text watermark is built from invisible Unicode characters — characters that render as blank space to your eye but carry machine-readable information. Our detector scans for every character class Anthropic uses:
Zero-Width Space
Takes up zero visual width. The most common marker, inserted between words or letters to encode tracking bits without changing layout.
Zero-Width Joiner
Forces adjacent characters to join into ligatures while remaining invisible itself. Serves as a deterministic machine insertion signature.
Zero-Width Non-Joiner
Suppresses ligature formation between characters; completely invisible to human readers but parsed by automated scanners.
Word Joiner
Blocks line breaks at specific character boundaries while occupying zero screen width. Frequently utilized in AI watermark arrays.
Bidirectional Control Characters
Controls bidirectional text ordering (e.g. Left-to-Right / Right-to-Left embedding overrides). AI watermark generators deploy these controls in micro-patterns across sentences.
Why Use This Claude Watermark Detector?
Engineered for accuracy, absolute user privacy, and complete transparency.
🔍 Transparent Results
Other tools say “AI-generated: 92%” with no explanation. We show you the exact characters, their Unicode codes, and where they sit in your text. You can verify every finding yourself.
🔒 Private & In-Browser
Detection runs entirely on your device. Your text is never uploaded, stored, or sent anywhere. Disconnect your internet after loading — it still works.
🎯 Claude-Specific
Built specifically for Anthropic's SynthID-Text scheme, not generic “AI detection.” It also flags watermark patterns from ChatGPT, Gemini, and DeepSeek.
⚡ Free, No Signup
No account, no email wall, no “3 free scans.” Paste and detect as many times as you need without restriction.
Detection vs. Removal — What's the Difference?
Detection tells you whether your text is watermarked and what is hiding in it. Removal strips those markers out and hands you clean text.
This page is the detector — run the scan first to inspect what invisible characters exist. If you already know you want clean copy, jump straight to our Claude watermark remover .
How Does Claude's Text Watermark Work?
In August 2026, Anthropic deployed SynthID-Text across all Claude models. The system weaves invisible Unicode characters into generated text, forming a pattern — a digital fingerprint — that search engines and AI-detection tools can read, even though the text looks normal to humans.
This is why text you wrote with Claude can suddenly trigger AI-content flags elsewhere: the visible words are yours, but the invisible markers still say “generated by Claude.” Detecting them is the first step to understanding what is being added to your content without your knowledge.
Frequently Asked Questions
Everything you need to know about detecting invisible Claude text watermarks.