Claude Watermark Checker & Detector | Unicode Scan
Check whether Anthropic's official Claude watermark detector/API is available, then scan text locally for hidden Unicode. The tool is private and free, but it does not produce an official watermark verdict.
Runs locally · No account required · No text storage
Evidence boundary
What this Claude watermark checker can verify today
| Evidence layer | Current status | What this page does |
|---|---|---|
| Claude statistical text watermark | API in private preview; not integrated here | Reports verification as unavailable; never invents a probability. |
| Hidden or unusual Unicode | Locally inspectable | Lists exact code points, counts, context, and conservative cleanup options. |
| C2PA file provenance | Relevant to supported files, not pasted text | Does not accept or verify files; use a C2PA-aware credential tool. |
Need the mechanism, rollout limits, code/proofreading caveats, and SynthID-Text explanation? Read the full Claude text watermark guide.
Paste text to inspect
Your text is analyzed locally in your browser for the currently available checks.
Analysis results
How to read the result
Inspect text integrity without overstating provenance
Start with the official verification status. When it is unavailable, the rest of the report is a local integrity inspection: it can reveal hidden Unicode and explain sample structure, but it cannot identify a human or AI author.
- Paste a representative passage and run the local analysis.
- Review every unusual character in context before removing it; some are legitimate language or formatting characters.
- Use the cleaned-copy preview only when you have confirmed that the selected invisible characters are unwanted.
WordPress publishing
Need a clearer review and publishing process?
I can help implement WordPress editorial roles, review steps and custom publishing features. Describe the problem and your website; we can agree a practical scope. This checker does not prove who wrote a passage.
Frequently asked questions
Clear boundaries for a privacy-first local inspection.
Can this tool verify an official Claude watermark?
Not with this tool. Anthropic offers a detection API in private preview to eligible organizations, but this checker has no supported integration. It reports official verification as unavailable; hidden characters and writing style do not establish authorship.
Does Claude currently watermark generated text?
Anthropic says Claude models launched in the EU on or after August 2, 2026 support machine-readable marking at launch, while support for earlier models is being added progressively. A missing or unavailable verification result therefore cannot prove that text is human-written.
Is the Claude watermark hidden Unicode or SynthID?
Anthropic says Claude uses a version of Google DeepMind's SynthID-Text approach. Nothing is added as a secret character: the statistical signal is created through otherwise-valid word choices during generation. Hidden Unicode is a separate text-integrity issue.
How can I detect Claude's official text watermark today?
Official statistical verification requires access to Anthropic’s compatible detector. Its detection API is in private preview for eligible organizations; consult the linked Anthropic guidance for access. This checker does not integrate that API, and Unicode scans or generic AI scores are not official verification.
Can this tool remove Claude's statistical watermark?
No. The cleaned-copy option removes only selected invisible Unicode characters. Anthropic says Claude's watermark is a statistical pattern in generated word choices, so Unicode cleanup must not be described as watermark removal.
Does hidden Unicode prove that text came from Claude?
No. Zero-width characters, non-breaking spaces, bidirectional controls, and variation selectors can come from copy-paste workflows, editors, languages, accessibility tools, or malicious manipulation. They are inspection signals, not proof of source or authorship.
Does my pasted text leave my browser?
No. The scanner, counts, suitability heuristic, cleaning preview, and copy action run in your browser. This page has no text-analysis API endpoint and does not store pasted content.
What does sample suitability mean?
It is a transparent structural heuristic based on length, prose continuity, repetition, and code-like content. It only indicates whether text could be useful to inspect if an official statistical method becomes available; it is not a watermark result.