SupWriter vs StealthGPT: Which One Actually Fits Your Work? (2026)

StealthGPT and SupWriter get compared constantly, and the comparison usually misses the point. These aren't two versions of the same product. One is built to write for you. The other is built to rewrite what you already wrote. That difference decides which one you should be paying for.

The indexable product landing for this split is StealthGPT vs SupWriter. This post is the long-form version.

Full disclosure up front: we build SupWriter. You should weight everything below accordingly. What we can promise is that we won't publish a StealthGPT number we can't source, we won't publish a SupWriter number we haven't measured, and we won't pretend StealthGPT is a bad tool. It isn't. It's one of the most recognizable names in this category.

Here's the honest breakdown.

Quick Comparison

StealthGPT details from its homepage, checked Sept 2026.

Two things about this table deserve a warning label. There are no "bypass rate" rows, because neither of us publishes numbers you could audit: SupWriter's own methodology page states that we haven't published live-detector bypass tests, and we couldn't find an independent StealthGPT test we could verify and cite. And the StealthGPT price is missing because its pricing page wouldn't load for us when we checked. Both are covered below. First, the difference that decides most of this.

The Biggest Difference: Generator vs Rewriter

StealthGPT's product line is wide. There's an AI Humanizer, but there's also Stealth Writer for generating essays with citations, a Stealth Agent that researches, drafts and refines, an SEO Writer, Chat with PDF, a Photo to Answers tool, and a Chrome extension. The pitch is that you can start from a prompt and finish with a document without ever opening a blank page.

SupWriter does one core thing. You bring text, and we rewrite it so it reads like a person wrote it. Around that sit an AI humanizer, an AI detector for a quick pre-check before you submit, a paraphraser and a grammar checker, plus the Chrome extension, iOS app, MCP server and API. Nothing in it will write the paper for you.

Which model is better depends entirely on what you're holding when you sit down.

If you have nothing (no draft, no notes, just a due date), StealthGPT's generation stack does something SupWriter flatly cannot. That's a real advantage and we're not going to argue around it.

If you already have a draft you care about, such as a dissertation chapter, a client deliverable or a paper with 30 citations in it, then generation is the wrong tool. You don't want new content. You want your content, preserved, made to read naturally. That's the case SupWriter is built for: rewriting what's there rather than generating something new.

A generation-first tool has a structural incentive problem here. If the model can rewrite freely, it will, because freer rewriting moves detector scores more. The cost lands on your meaning, and you often don't notice until a reader does.

Detector Performance: Read This Section Carefully

This is the section most comparison posts fill with percentages. We're going to disappoint you on purpose.

What we don't have. SupWriter has not run live, published tests of its output against Turnitin, GPTZero, Originality.ai or Copyleaks, and our methodology page says so. We also couldn't find an independent StealthGPT review whose numbers we could check, so we're not quoting any.

What independent research does show. One independent source did test StealthGPT specifically. In a 2025 working paper, Brian Jabarian and Alex Imas of the University of Chicago Booth School of Business ran AI-written passages through StealthGPT's default rewrite and re-scored them with four detectors (Jabarian and Imas, 2025). They found:

• Pangram's performance was "largely robust to the humanizer", detecting nearly all of the rewritten AI text on longer passages.
• Originality.ai's miss rate rose to around 5% on longer text and up to 21% on shorter text, so it still caught most of the StealthGPT output.
• GPTZero "largely loses its capacity to detect" the rewritten text, with miss rates around 50% and above across most genres and models.

That's one study, with one humanizer and one setting, and detectors have changed since. But it's a useful corrective to the idea that any humanizer makes text invisible. If Originality.ai is what your publisher or client runs, that's the result that matters to you; our guide on how to bypass Originality.ai explains why that detector behaves differently from the rest.

Detectors keep moving, too. Turnitin added detection of text modified by "AI humanizer tools" on 27 August 2025, for English submissions (Turnitin announcement). On 4 August 2026 it announced a simpler report with a single highlight for all likely AI writing "regardless of whether the text was copied directly from an LLM or run through secondary AI paraphrasing and bypassing tools" (Turnitin blog). Any bypass number published before those changes describes a detector that no longer exists.

To be fair to StealthGPT: no tool can guarantee a result, including ours. SupWriter rewrites AI-assisted drafts so they read naturally, and you can check the output with the built-in detector before you submit. That detector is a pre-check based on one scoring model, not the detector your school uses, and results vary by detector, text length and topic. Anyone selling you certainty is selling you something.

Before and After: What Rewriting Looks Like

Here's a paragraph straight out of an AI model, the kind of thing detectors eat for breakfast:

Furthermore, it is important to note that remote work has fundamentally transformed the modern workplace. Studies have consistently demonstrated that employees who work remotely report higher levels of job satisfaction. Additionally, organizations have realized significant cost savings through reduced office space requirements. In conclusion, remote work represents a paradigm shift in how we approach professional environments.

Four sentences, four textbook AI tells: the "furthermore" opener, the uniform sentence length, the vague "studies have consistently demonstrated" with no study attached, and the "in conclusion" landing pad on a paragraph that isn't a conclusion.

Here's the same paragraph rewritten the way a good humanizer pass should read:

Remote work has changed how offices operate. Study after study finds that people who work from home report higher job satisfaction. Companies found a second benefit: they stopped paying for square footage nobody was sitting in. Taken together, that's a genuine shift in how professional work gets done.

The meaning is intact. What changed is the shape: sentence lengths now run from seven words to fifteen, the connective tissue does actual work instead of signposting, and the vague claim reads like a person summarizing rather than a model hedging. That variation is one of the things detectors measure, and synonym swapping rarely produces it.

Notice what did not happen: no new claims got invented, no statistic appeared out of nowhere, no argument flipped direction. That's the constraint a rewriter should operate under, and a generator doesn't.

Academic Work: Citations Are the Dividing Line

If you're a student or researcher, this is the section that should decide it.

A paper with mangled references is its own integrity problem, whatever a detector says. Author names, publication years, page numbers, DOIs and formatting conventions across APA, MLA, Chicago, IEEE and Vancouver all have to survive any rewrite exactly. Neither SupWriter nor StealthGPT publishes an audited citation-preservation figure, so don't take either tool's word for it. Check it yourself:

1. Keep a copy of your reference list before rewriting.
2. After rewriting, compare every in-text citation and reference against the original: names, years, page numbers, DOIs.
3. Re-check any quotation word for word. A rewriter should leave direct quotes alone.

StealthGPT's Stealth Writer advertises generating essays with citations, which is a different and, frankly, riskier proposition. Language models are known to produce plausible-looking references that don't exist, so every generated citation needs verifying against the real source. A rewriter working on your existing, already-verified citations avoids that failure mode, as long as you confirm the citations came through intact. More on academic workflows in our guide to the best AI humanizer for academic papers.

If you're writing something with a bibliography, that distinction is not a nice-to-have.

Languages

StealthGPT's homepage advertises humanizing "across 250+ languages". SupWriter's language support covers 50+ languages in the editor. On the raw count, StealthGPT's claim is far larger, and we'll say so plainly.

The count isn't the useful metric, though. A long language list tells you what a tool accepts, not how well it rewrites each language. When we ran non-English drafts through SupWriter and scored them with our own detector, results were mixed: most Tagalog runs dropped to low scores, our detector couldn't judge Malay at all (it scored human-written Malay as 100% AI), and for several other languages it couldn't judge the text reliably either. The details, including the failures, are in our post on AI humanizers for non-English content.

We haven't tested StealthGPT's non-English output ourselves, so treat that column as unverified. If you write in a language other than English, the advice holds either way: ignore the number on the features page, run a paragraph through, and have a native speaker read it. The output tells you what the marketing won't.

Pricing and Free Tiers

SupWriter's list prices start at $9.99 a month for 5,000 words (Basic), or $4.99 a month billed annually. Pro is $19.99 a month for 15,000 words and Ultra $39.99 for 30,000, and annual billing halves each. The free tier is 300 words in total, one-time; it needs a free account but no credit card.

StealthGPT's pricing page wouldn't load for us when we checked in September 2026, so we're not quoting a price. Check its current plans on stealthgpt.ai before you compare. Its homepage does advertise a free AI detector with "no signup required", but it doesn't state a free humanizing allowance.

That last part matters more than the monthly delta. A free humanization tier is a testable claim: when a tool lets you paste real text and read the output before paying, you can verify the marketing yourself. Our free humanizer exists for exactly that reason, and we'd give the same advice about any competitor that offers one.

What StealthGPT Genuinely Does Better

Three things, and they're not small.

Generation. If you need content that doesn't exist yet, StealthGPT produces it and humanizes it in one flow. SupWriter has no answer to that workflow. You'd need to generate elsewhere and bring the draft to us.

Breadth. The SEO Writer, Chat with PDF, Photo to Answers and the Chrome extension add up to a toolkit, not a single feature. For someone who wants one subscription covering several jobs, that consolidation has real value.

Brand recognition. StealthGPT is one of the best-known names in this category. That's worth something when you're choosing a tool you'll rely on under deadline pressure.

Who Should Choose Which

Choose StealthGPT if you're starting from nothing and want the draft generated for you, you want several adjacent tools under one subscription, or you value an established brand over a specialist one.

Choose SupWriter if you already have a draft, you're working on academic writing where citations and technical terminology must survive intact, or you want a detector pre-check, grammar checker and paraphraser in the same editor as the rewriter.

Whichever you pick, remember that detector results vary between tools, versions and even runs. For a graded submission, the cost of the one draft that gets flagged isn't proportional to the number that didn't. We've written more about that risk in our piece on whether Turnitin can detect ChatGPT.

The Verdict

For rewriting a draft you already have, especially academic work where your citations and your argument have to survive, SupWriter's rewrite-first design is the better fit, and you can judge it on 300 free words.

For generating content from scratch inside a broader toolkit, StealthGPT is the better fit, and we'd rather tell you that than pretend otherwise.

And since we're the biased party here: don't take our word for it. Take a paragraph you wrote with AI help, run it through both, read the results, and check them against whatever detector actually matters to you. Ninety seconds of your own testing beats any comparison table, including this one.

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