StealthGPT Review (2026): It Beat GPTZero, But Sapling Still Caught It

StealthGPT is a real AI humanizer that works, with some catches. In the HumanizerPRO team's September 2026 test, its default "Super" model turned our unedited GPT-4o text into fluent writing that GPTZero rated 1% AI and ZeroGPT rated 0% AI. But Sapling still flagged the same output as 77.8% AI, the quality changed from run to run, and the paid plans are pricey: $29.99 a month (after a $1 intro price) or $6.99 a week, with no refunds. We rate it 7 out of 10. SuperHumanizer and HumanizerPRO passed all three detectors in our tests and cost less.

StealthGPT at a glance

What is StealthGPT?

StealthGPT is an AI humanizer at stealthgpt.ai, made by XYZ AI Inc. Paste in text from ChatGPT, Claude or Gemini, and it rewrites it to sound more human, so AI detectors are less likely to flag it. Its latest model is called "Super". The paid plans add an AI detector, file uploads, in-text citations, 100+ languages, an iOS app, a Chrome extension and, for Enterprise customers, API access.

StealthGPT isn't the same as StealthWriter, but the two are easy to confuse: one of the testimonials on StealthGPT's own homepage even mentions StealthWriter. If that's the tool you're looking for, see our StealthWriter review.

How we tested StealthGPT

In September 2026, the HumanizerPRO team tested StealthGPT on the same unedited GPT-4o passage we use for every humanizer review: a 306-word post about a new blood test that estimates biological age. Before humanizing, GPTZero and ZeroGPT both rated the passage 100% AI.

We used the free humanizer on StealthGPT's homepage with its default Super model, without creating an account. We copied the output exactly as returned, tested it on GPTZero, ZeroGPT and Sapling, and compared it with the original sentence by sentence. We also ran a second, 190-word sample to check consistency.

Does StealthGPT bypass AI detectors?

For the most part, yes. GPTZero was "highly confident" StealthGPT's output was entirely human and rated it 1% AI, 99% human, one of the best GPTZero results we've recorded. ZeroGPT rated it 0% AI and called it human-written.

Sapling disagreed. It rated the same text 77.8% AI, which most teachers or editors would treat as AI-generated. That's the main risk with StealthGPT: it's tuned to beat the most popular detectors, but not every detector. You can't choose which detector your school, client or publisher uses, so a tool that fails even one of them is a gamble. For how much these scores can vary, see are AI detectors accurate?

How good is StealthGPT's writing?

In our main test, the writing was good. StealthGPT rebuilt the post into four clear paragraphs and kept the facts: the test reads hundreds of proteins, it can spot problems before symptoms appear, people can track how diet and exercise affect their biological age, and it still needs validation in larger, more diverse groups. It reads like a tidied-up news summary, although it added one small claim the original didn't make: that doctors can see "how different organs are functioning".

The second run was weaker. StealthGPT added the chatty line "What's so cool about this?" and finished with "This is a great advancement in personalized medicine that should interest longevity seekers", which doesn't suit a neutral article. One sentence also lost its meaning, saying that people who want to extend their healthspan "can use biological aging for early diagnoses of disease".

So the quality is good, but it varies from run to run. If you use StealthGPT for school or client work, review every output before you submit it.

StealthGPT pricing and plans

StealthGPT has weekly, monthly and yearly billing:

Keep three things in mind. First, the $1 introductory price renews at the full monthly rate until you cancel. Second, weekly billing adds up: $6.99 a week is roughly $30 a month. Third, StealthGPT's terms say all purchases are non-refundable, with one exception: its "Detected? Get your money back" guarantee. If you send a screenshot showing a valid AI detector flagged its output, weekly and monthly users get their current billing period refunded.

By comparison, HumanizerPRO's Pro plan gives you the same 50,000 words a month, with 1,200 words per input, for $12 a month billed yearly, and it includes a 3-day money-back guarantee. If you need an API, StealthGPT offers one on its Enterprise plan; compare other options in our list of the best AI humanizer APIs.

StealthGPT pros and cons

What's good

• Beat GPTZero (1% AI) and ZeroGPT (0% AI) in our test
• Free homepage humanizer worked without an account, twice
• Fluent writing in our main test, with the key facts kept
• iOS app, Chrome extension, file uploads and 100+ languages on paid plans

Downsides

• Sapling still flagged its output as 77.8% AI
• Quality varied between runs, with a chatty tone and one muddled sentence
• Expensive: $29.99 a month, or $24.99 a month billed yearly, for 50,000 words
• Purchases are non-refundable outside its detection guarantee
• 1,000 words per request on Pro, less than HumanizerPRO's 1,200

StealthGPT vs. SuperHumanizer vs. HumanizerPRO

StealthGPT had the lowest GPTZero score, but it was the only one of the three that failed a detector. SuperHumanizer, our sister tool, passed all three and is completely free, with no sign-up and 1,200 words per run. It also has a Chrome extension and Android and iOS apps. HumanizerPRO passed all three as well, and its paid plans cost about half of StealthGPT's. It also includes a free AI detector and plagiarism checker, so you can check your text before you submit it.

Is StealthGPT worth it?

StealthGPT is worth it if GPTZero is the only result that matters to you and you have no problem paying around $25 to $30 a month with no refund. Its GPTZero result was one of the best we've recorded.

For most people, it isn't the best value. Its output failed Sapling, its quality changed between runs, and the same number of words costs less than half as much elsewhere. Start with SuperHumanizer if you want free humanizing, or HumanizerPRO if you want a paid plan with more words per input, a money-back guarantee and built-in checking tools. For more options, see our ranking of the best AI humanizers.

Frequently asked questions

Is StealthGPT free?

StealthGPT's homepage humanizer let us humanize text without an account, up to 1,000 words per request, in September 2026. Its paid plans start at $6.99 a week, or $29.99 a month after a $1 introductory price. SuperHumanizer is completely free, with no sign-up and 1,200 words per run.

Does StealthGPT bypass GPTZero?

Yes, in our test. GPTZero rated StealthGPT's output 1% AI and 99% human. ZeroGPT rated it 0% AI. Sapling, however, rated the same text 77.8% AI.

Does StealthGPT bypass Turnitin?

StealthGPT says it does, but we couldn't check, because Turnitin is only available through schools. Since August 2025, Turnitin also flags text it suspects was changed by AI humanizers or bypass tools.

Is StealthGPT the same as StealthWriter?

No. StealthGPT (stealthgpt.ai) and StealthWriter (stealthwriter.ai) are different humanizers from different companies. Read our StealthWriter review for that tool.

Can I get a refund from StealthGPT?

Only in one case. StealthGPT's terms say all purchases are final unless they qualify for its "Detected? Get your money back" guarantee. If you send a screenshot showing a valid AI detector flagged its output, weekly and monthly users get their current billing cycle refunded.

What is the best StealthGPT alternative?

SuperHumanizer is the best free alternative: it's 100% free, needs no sign-up and passed GPTZero, ZeroGPT and Sapling in our test. HumanizerPRO is the best paid alternative, with plans from $7 a month billed yearly, up to 3,000 words per input and a 3-day money-back guarantee.