Claude Copyleaks checker

There is no affiliation between this tool and Copyleaks, no licence, no integration and no access to their systems. It follows that no result produced here corresponds to, approximates or predicts a Copyleaks scan. A page that implied otherwise would be selling a capability that does not exist, and this one states the boundary before anything else.

Inside that boundary the tool does something real. Pasted text is analysed on our server and the result is a written account of observable qualities in the writing, with its own limits attached. Envelope: 5 runs per rolling 24 hours, 1 to 12,000 characters, an optional 300-character instruction, no account and no retained history.

The unit you submit determines the resolution of what comes back.

Step 1

Submit a bounded passage. A whole document produces general observations; a section produces observations you can test line by line.

Step 2

State a criterion in the instruction field rather than a subject. A criterion can be answered; a subject invites a summary.

Step 3

Verify each finding against the text. Any that survives verification is worth acting on, and any that does not costs you ten seconds.

Copyleaks' API documentation describes three outputs: "a per-section classification (human or AI)", "an overall human-versus-AI summary", and "AI Logic explanations of why content was flagged", the last including the highlighting of "specific sentences that sound like AI writing". It states support for "30+ languages, including English, Spanish, French, German, Chinese, and Arabic", and it sets out no minimum or maximum text length.

The framing around those outputs is advisory rather than evidentiary. The documentation says results help you "make confident decisions about content authenticity" and "make informed choices", which locates the judgement with the reader rather than in the number. That is a more careful position than most of the review layer around this term represents it as being.

A published review of the tool records "a likelihood score and sensitivity options", with "adjustable sensitivity settings" for different use cases, and cites a low false positive rate where "human written texts are rarely mislabeled as AI generated". Take the two together and the consequence is structural: where the line falls between flagged and not flagged is a configuration decision made by whoever runs the scan.

A property of a text does not move when someone adjusts a control. So an output that does move is better understood as a risk posture than as a measurement. This route therefore produces no score, and there is no threshold on it to edit toward, which removes the optimisation game entirely rather than pretending to referee it.

Copyleaks ships plagiarism detection and AI detection separately, and the alternatives-listing pages that crowd this term collapse the two. The distinction matters because the evidence base is completely different: similarity is a retrieval problem against a corpus, while AI detection is a classification problem over surface statistics.

This route performs neither. There is no corpus, no index, no retrieval and no matching, so no similarity claim is possible. And no classifier here labels a span, so no AI verdict is produced. What remains is an editorial reading, which is a smaller claim and a verifiable one.

Everything else in this category is speculation about an invisible output. These two are not.

The quality of the writing

Repetition, uniform paragraph openings, sections that do not deliver their heading. These are fixable and the fix survives every scan, because it is a change to the text.

The record of how it was made

Drafts, timestamps, notes, version history, sources actually consulted. This is the only material that speaks to process, and it must exist before the question arises.

Not: a target score

You cannot see the result, so you cannot optimise against it. Editing blind degrades prose without any evidence it moves anything.

Not: a guarantee

No tool can promise a verdict from an instrument it does not run. Any page offering that is describing something it has no access to.

The review we read describes the commercial side as "limited free access for testing", with "Full AI detection and plagiarism checking require a paid plan" and pricing that "may not suit occasional users" because the product targets professional and organisational buyers. That is a coherent model for an institutional tool and not a criticism.

The model here is different in kind rather than in degree: 5 runs per rolling 24 hours, no account, no payment path, nothing stored and no higher tier in existence. There is no upgrade to withhold features for, which is why the limits page below is a complete list rather than a teaser.

No affiliation, no access to Copyleaks, no predicted or approximated result from them or from any other detector. No percentage, likelihood score, sensitivity control, per-section classification or sentence highlighting. No plagiarism index, similarity report or source list.

No file upload; pasted text only, bounded at 12,000 characters. No language count, where their API documents 30 or more, because nothing here establishes one. No accuracy or false positive figure, because none has been measured on this engine and importing theirs would describe a different instrument. No authorship claim about any model or any person, on any run.