Stealthly review

Stealthly gives 300 free humanizer words a month at 80 words per request and sells Basic at $17.00 a month, or $11.00 a month on the yearly toggle, for 20,000 words a month and 400 words per request, read on its pricing page on 9 November 2026. This Stealthly AI review covers what each plan buys, what the vendor claims about its output, and where the tool sits against the others in the full humanizer ranking under one published method. Stealthly is not StealthGPT and not StealthWriter; the first of those is covered in the StealthGPT review.

What does Stealthly itself claim?

The homepage carries three figures in one strip, read 9 November 2026: trusted by more than 700,000 professionals, trained with more than 10 million texts, and 99.6 percent or more of outputs passing as human. A heading further down the same page states a 96 percent or higher success rate. Two success figures on one page, with no input set, no date and no method for either, cancel each other out as evidence; a reader cannot tell which one the vendor stands behind.

The homepage also lists the detectors it says it has been tested against: Originality.ai, Turnitin, GPTZero, ZeroGPT, Copyleaks, Winston AI, Sapling, Crossplag and Content at Scale, read 9 November 2026. The pricing page splits that list into two tiers, "basic AI detectors" such as ZeroGPT and Sapling and "the strictest" such as Originality.ai, Turnitin and GPTZero, and claims both tiers on every plan including the free one. Turnitin's detector is not available to the public, so this site reports only what Turnitin publishes and what peer-reviewed studies found, never a Turnitin pass or fail.

What does the research say about paraphrased text?

Stealthly describes itself as a deep learning rewriter that finds the AI-sounding parts of a text and restructures them, read 9 November 2026. The published research on paraphrase explains why that moves detector readings and why it is not the whole story. Weber-Wulff and colleagues tested 14 AI text detectors and found every one below 80 percent on their accuracy measure, with accuracy falling further on paraphrased text (Weber-Wulff et al. 2023, International Journal for Educational Integrity, read 9 November 2026). Krishna and colleagues showed that a paraphrase model dropped DetectGPT's detection rate from 70.3 percent to 4.6 percent at a 1 percent false positive rate (Krishna et al. 2023, arXiv, read 9 November 2026).

Detector makers answer in kind. GPTZero states that its model shields against common evasion methods, paraphrasing among them, and keeps its false positive rate at no more than 1 percent when evaluating AI against human text (GPTZero, How GPTZero works, read 9 November 2026). A humanizer and a detector are moving targets for each other, and a reading is true for its date.

What none of those pages measure is whether the rewrite kept the writer's claims. That is why the method on this site weights meaning kept at 35 points of 100, errors added at 20, detector pass rate at 30 and limits and access at 15. No detector score should be the only evidence in a misconduct case.

What about the built-in checker?

Every Stealthly plan includes an AI checker with its own monthly word allowance, from 300 words free to 500,000 on Premium, read 9 November 2026. The pricing page says it detects text from several model families and nothing about its method or rates. A vendor's own checker is not independent evidence about that vendor's humanizer, because the same company wrote the rewrite and the verdict; the vendors that ship both are compared in the humanizer and detector list.

What does Stealthly change in your text?

The homepage names three modes under the label Humanizer 2.0, Light, Balanced and Deep, read 9 November 2026, and describes neither the difference between them nor which is the default. The names imply a ladder from a lighter touch to a heavier rewrite. The site's protocol runs each tool on its default mode and, where a stronger documented mode exists, that mode as a second row, so a published run will show Stealthly twice.

The vendor states that the tool fixes mistakes in the input and returns text free of grammar, punctuation and spelling errors, and that it keeps the original meaning, read 9 November 2026. Those are the two claims the method can test directly: errors introduced per 100 words, counted by two editors, and claims kept, rated blind on a 1 to 5 scale. The figures appear here once a run is published.