Claude GPTZero checker

GPTCleanup Pro's Claude GPTZero checker reads a passage and reports the rhythm patterns typical of Claude's default voice, the hedged, clause-heavy sentences a perplexity-and-burstiness style checker tends to weigh, with each pattern named and explained rather than compressed into a single guessed number.

It's a server tool by necessity. Scoring against a rhythm-pattern model is too heavy to run in a browser, so text is sent to our AI server and the result returns to the page. You get 5 free checks in any rolling 24 hours, no account required.

The output is a list, deliberately. A checker that returns a bare percentage is asking for unearned trust; this one names each pattern (a hedging opener, an elevated clause count, a run of uniform sentence length) so the reasoning is available for inspection.

Perplexity quantifies how predictable each next word is to a language model. Claude's careful, hedged phrasing tends toward safe, expected word choices, which tends to register as low.

Burstiness measures how much that predictability varies across a document. Claude's long, clause-stacked sentences can look bursty in raw length while staying low-perplexity in word choice, an unusual combination that rewards a closer read rather than trust in a single figure. Neither measure is proof on its own; both are imperfect statistical proxies.

One round trip to the server, then a reasoned result. No configuration required beforehand.

Step 1

Paste the sample. A longer passage gives the model more rhythm to measure than a single sentence would.

Step 2

Run the check. The text is sent once to our AI server, scored against Claude's writing patterns, and nothing further is done with it.

Step 3

Review each flagged pattern and its stated reasoning, an argument you can inspect rather than a number you're asked to trust.

No, and stating that plainly is more useful than avoiding it. GPTZero's exact scoring model, decision thresholds and training data are proprietary, and the company revises them without public notice. Any claim to reproduce its output would be guesswork dressed up as precision.

This tool has no access to that system, so what it offers instead is a defensible, separate signal: whether the writing carries rhythm patterns typical of Claude's default voice.

Low perplexity and hedged phrasing are not unique to Claude. Several categories of honest writing share the same cautious rhythm for reasons that have nothing to do with a chatbot.

Second-language writers

Formal connectors and explicit hedging are standard ESL instruction, and produce exactly the pattern this checker looks for.

Careful academic prose

Deliberate hedging is good scholarship, and it produces the same low-perplexity phrasing this check weighs.

Neurodivergent writers

Naturally structured, qualified sentences read as machine-typical to a burstiness check, independent of authorship.

Heavily edited Claude drafts

Sentence-by-sentence human rewriting can raise both measures without the underlying content becoming genuinely different.

A flag from this tool, or any detector, is a signal rather than a finding. Institutions set their own policy for what follows, and evidence of process is the strongest response available.

Preserve your drafts

Outlines and earlier versions are the clearest evidence a piece was composed, not generated whole.

Retain version history

Docs, Word and most editors log revisions automatically; leave it intact while a question is open.

Ask for the named signal, not the label

A specific pattern can be examined on its merits. An unexplained score cannot.

The same checker, applied at different points in a review process.

Students

A private, informal read before submission, alongside their own honest review of the draft.

Editors and reviewers

A first pass on incoming drafts that read unusually hedged before committing editorial time.

Hiring reviewers

Checking whether a writing sample's rhythm matches the rest of an application.

This checker is server-side by design: scoring against Claude's writing patterns requires a model too large to ship into a page, so each check is a single round trip rather than local computation.

That trip is metered rather than unlimited: 5 free checks in any rolling 24-hour window, tracked without an account. It reopens as the window rolls forward rather than resetting at a fixed hour.