A watermark is a generation signal
Claude’s watermark is introduced while the model chooses its words. Copying the same wording into a new document does not turn it into a different sequence.
Claude Watermark Detector
Know what is in your draft. Understand what the signal means.
Paste your text to check AI-writing patterns, then explore how Claude’s watermark works. A useful starting point for reviewing essays, articles, emails and other AI-assisted writing.
Text workspaceDraft analysis
Free tryUp to 500 words
Made forEssays, articles & everyday writing
Check your Claude draft
Paste a passage below to get started. Free try up to 500 words.
Words limit: 0 / 500
Does Claude have a watermark?
Yes. Anthropic uses an invisible statistical watermark in supported Claude models. The signal lives in the choices between plausible words, rather than hidden spaces, extra characters or a tag attached to your document.
The scope depends on the model and platform. Anthropic publishes its current coverage and offers official watermark detection in private preview for eligible organizations.
Read the official sourcesClaude watermark detection, explained
Three distinctions make a draft review more useful.
An AI score answers a different question
A general AI checker estimates patterns associated with AI writing. It does not use Anthropic’s watermark key or identify a specific Claude account.
Your review still matters
Use your drafts, sources and revision history alongside any score. Read the passage for accuracy and whether it says what you actually mean.
See the difference between the signals
Watermarking, AI classification and invisible characters are different things. Explore the illustration to see what each one looks for.
A signal in the word choices.
A provider introduces a statistical pattern while generating text. Official verification checks for that provider’s signal using the matching key or service.
Question: does this text carry the provider’s signal?
Illustrative word choices
The groupcomparedthree approaches.
consideredcomparedreviewed
Natural wording. A pattern across many choices.
Conceptual illustration. No text has been analyzed here.
How to check a Claude draft
A straightforward path from the first paste to your next edit.
Paste your draft
Add the Claude passage you want to review. Keep enough surrounding text to give the check useful context.
Run the check
Read the returned AI-writing score alongside the text, rather than guessing from a phrase or punctuation mark.
Decide what to edit
Use the result as one part of your review. Check the facts, sources and voice before you share the draft.
Anthropic’s official detector checks whether word choices match the statistical pattern associated with its watermark key. This page offers an AI-likelihood check, which analyzes writing patterns rather than verifying that official signal.
Anthropic says its text watermark does not add hidden characters. It changes the source of randomness used to choose between plausible words while generating a response.
A general AI detector and a keyed watermark detector use different methods. An AI-likelihood score can help you review a draft, but it does not confirm the presence or absence of Anthropic’s official watermark.
Coverage depends on the supported model and platform. Anthropic’s help center keeps a current coverage matrix, including the transition for older models.
No. Anthropic says the watermark does not identify an individual, organization or conversation. It is a signal about the model’s involvement in the text.
Yes. Use StealthGPT’s Claude watermark remover page to rewrite the wording and sentence structure, then compare the result with your original draft.
Yes. The page offers a free try for up to 500 words, subject to availability and usage limits. For continued access, compare the current StealthGPT plans.
Go straight to the source.
Official references for the watermark facts on this page.
- AnthropicHow Claude’s text watermarking works
The source of the signal, how it behaves, and what it can tell you.
- Claude Help CenterCurrent Claude marking coverage
Supported models, products and official detection access.
Give your draft a closer look.
Start with the text. Check the writing patterns, understand the signal, and choose your next edit.
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