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Simple Unmark

Documented as of August 2026

Claude Watermark Remover for Text

Anthropic documents a key-based watermark woven into Claude's token choices, and states that nothing is added to the text and there are no hidden characters. Because the mark lives in the wording, a thorough rewrite is what addresses it — which is what this tool does.

Original

Local scan runs as you type.

Hidden-character cleanup + wording rewrite

Anthropic Claude: current status

Last verified · first-party documented

Anthropic documents a text watermark in Claude output, applied globally, using a SynthID-Text-style token-choice method.

Status
Rolling out
Mechanism
A key-based pattern in low-stakes token choices. Anthropic describes using the key plus the preceding words to settle which word the model picks, and states the approach is a version of the SynthID-Text method published in Nature.
Hidden characters involved?
No. Anthropic states plainly that nothing is added to the text and that there are no hidden characters.
Public detector
Anthropic says a watermark detection API will be offered but that implementation details are still being worked out, so no public detector was available at the verification date.

What the provider says weakens the signal

  • Anthropic states light editing probably will not remove it, while a complete rewrite in which every word is replaced will
  • Text Claude only lightly edited, because few of the words are Claude's
  • Factual passages and code, where there are fewer free choices to encode
  • Small samples, where detection does not work well

How this works

Deterministic marks can be removed exactly. Probabilistic patterns can only be reduced. Simple Unmark keeps the two separate and does not promise detector outcomes.

  • Anthropic describes the watermark as using the key plus the preceding words to settle which word the model picks, and identifies it as a version of the SynthID-Text approach published in Nature in 2024. It applies globally rather than only in the EU.
  • Anthropic is explicit that light editing probably will not remove the watermark, while a complete rewrite in which every word is replaced will. A few swapped words is therefore not a serious attempt; a full restructuring is.
  • Anthropic also notes the mark is sparser where Claude had fewer free choices — factual passages and code — and that detection does not work well on small samples. Text Claude merely proofread carries very little, because nearly all the words are the person's.

Three steps

  1. 1

    Paste the Claude text. The local scan reports any invisible characters, which come from the copy path rather than from the watermark itself.

  2. 2

    Run the clean. The rewrite is the step that matters for this watermark: it replaces Claude's token choices throughout rather than editing lightly.

  3. 3

    Check the rewrite preserved your facts and figures, then copy it.

Worked example

Before

A Claude response pasted from the chat: Claude's own token choices throughout.

After

A full restructuring: new clause order, transitions and vocabulary across the passage.

Anthropic states that no characters are added, so a hidden-character scan of Claude text will often be empty and that is expected. The rewrite is the operative step, and its output varies per request.

Scope

What this page can and cannot do

Can

  • Replace Claude's token choices across the whole passage, which is the change Anthropic describes as removing the mark
  • Clean invisible characters that entered through a browser, editor, CMS or collaboration tool
  • State the current status with a first-party citation and a verification date

Cannot

  • Check for the watermark: Anthropic says a detection API is planned but was not publicly available at our verification date
  • Guarantee that every trace is gone, since we cannot measure what we cannot detect
  • Strip C2PA provenance metadata from files — this tool handles pasted text, not file metadata
  • Tell you whether a given passage was written or merely edited by Claude; Anthropic notes the mark cannot distinguish those either

Submitted text and cleaned output are not stored in our application database, and no text is ever sent to analytics. Deterministic inspection on the invisible character remover runs entirely in your browser. See the privacy policy and methodology.

Questions

About claude watermark remover for text

Sources

Does Claude watermark text?
Yes, per Anthropic's own documentation published in August 2026: supported Claude models weave a machine-readable watermark into generated text, applied worldwide. Models launched before 2 August 2026 were to be updated over the following months. See the dated status block above.
Is it a hidden Unicode character I can strip?
No. Anthropic states directly that nothing is added to the text and there are no hidden characters. Tools that claim to strip a Claude watermark by deleting invisible characters are not addressing this mechanism.
Does the watermark survive copy and paste?
Yes. It is part of the word choices themselves, so copying, pasting and reformatting carry it along. Anthropic says light editing probably will not remove it.
Does the watermark prove Claude wrote something?
No, and Anthropic says so explicitly: it can only indicate Claude was likely involved at some point, and cannot separate "Claude wrote this" from "Claude heavily edited this". It says nothing about ownership or authorship.

Other cleaners

Need more than three cleans?

Credits cost 0.1 per started 100 words, never expire, and there is no subscription. An account raises the limit to 5,000 words per clean.

See pricing