AI Rephraser · comparisons
StealthZero vs QuillBot: A Practical 2026 Comparison
StealthZero vs QuillBot compared on what each is actually built for, real 2026 pricing from each vendor's page, and which one fits the work you're doing.
QuillBot and StealthZero get compared a lot. They show up in the same search results, both have free tiers, both target writers, and the conclusion you’ll read in most listicles is “StealthZero is better” or “QuillBot is better,” depending on who wrote it.
The honest answer is neither. They solve different problems and the pricing has converged enough that the question isn’t price, it’s fit.
This post is a direct comparison grounded in two sources: QuillBot’s live pricing page (captured 2026-05-28) and StealthZero’s verified product specifications. Where we cite QuillBot’s claims, we mark them as theirs. We don’t include fabricated “QuillBot output” examples or made-up bypass benchmarks.
What is the category difference between StealthZero and QuillBot?
QuillBot is a 10-feature writing suite ($8.33/mo annual); StealthZero is a specialized AI humanizer + detector with 5 rewrite models, two detector engines (E.D.I.T.H + Sentrio v2, 100-word minimum, 4 modes), and four-detector Proof Reports. The Cohera Jarvis sub-model reaches 100% bypass in internal testing.
The first thing to understand is that QuillBot in 2026 is not the QuillBot of 2022.
What QuillBot is
QuillBot Premium is a writing suite. Its own positioning on the premium page: “the only AI subscription you’ll ever need.” The Premium bundle, per quillbot.com/premium:
- Paraphraser (unlimited words, all modes, 8+ standard modes plus custom modes)
- Grammar checker (advanced recommendations)
- AI humanizer (unlimited words on Premium; 125 words / 6 uses per day on Free)
- AI detector (limited on Free, unlimited on Premium)
- Plagiarism checker
- Summarizer (custom summaries on Premium)
- Citation generator
- Translator
- AI Chat
- AI Image Generator
- Browser extensions and native apps
Sadasivan et al. 2023 (arXiv:2303.11156) showed that even the strongest AI text detectors degrade toward random-chance accuracy under light paraphrasing attacks, suggesting a theoretical ceiling on reliable detection of high-quality AI text.
That’s a wide-suite product. The pricing reflects bundle economics: one $8.33/mo annual subscription, every feature.
What StealthZero is
StealthZero is specialized. Here is what the product ships:
- AI humanizer with 5 rewrite models (Origin / Sentinel-Lite / Sentinel-Max / F.R.I.D.A.Y / Jarvis), tone + readability + purpose controls, locked phrases, protected keywords
- AI detector with two engines: E.D.I.T.H (Shield-Lite) and Sentrio v2 with 4 modes
- Multi-detector AI Reports, Turnitin parity + GPTZero + Winston + CopyLeaks in one PDF
- Jarvis Agent for multi-step research and writing tasks
- AI Writer for document generation
The product is narrower on purpose. The Rephrase tool is the headline; everything else exists in service of “rewrite text so it reads as human, then prove it.”
If you look at the homepages side by side, the framing tells you everything. QuillBot leads with breadth, “the only AI subscription you’ll ever need.” StealthZero leads with a specific outcome, humanize, verify, prove.
Rephraser quotas and pricing at a glance
Free tier covers 600 rephrase requests per month with a 20-per-day cap and unlimited words per request. Pro covers 3,000 advanced model requests at $19.99/month. Auto Agent Rephrase batches up to 12,000 words per task.
- Free plan: 600 requests/month, 20/day cap, unlimited Origin model
- Starter ($9.99/mo): unlimited Origin + 1,500 advanced requests (50/day cap)
- Pro ($19.99/mo): 3,000 advanced requests (100/day cap), 80+ languages, API access
- Premium ($29.99/mo): unlimited all models, 100+ languages, 5 Auto Agent credits
- Auto Agent Rephrase add-ons: Mini $3.99 (2,000 words), Pro $6.99 (5,000 words), Max $12.99 (12,000 words)
- Liang et al. 2023 (arXiv:2304.02819) documented over 60% false-positive rates for ESL writers across mainstream GPT detectors
Weber-Wulff et al. 2023 (Int J Educ Integr 19:26) benchmarked 14 detection tools and found none reached the accuracy needed to be considered reliable in academic integrity workflows — most tools either over-flagged human writing or missed machine-paraphrased AI text.
Pricing — captured 2026-05-28
QuillBot pricing
| Tier | Annual (per month) | Notes |
|---|---|---|
| Free | $0 | Paraphrase 125 words; 2 modes; humanize 125 words / 6 uses per day; limited AI Detector |
| Premium | $8.33/mo | Unlimited paraphrase, all modes, advanced grammar, unlimited humanizer with human-score + tone insights, unlimited AI Detector, plagiarism prevention, custom summaries |
| Team Plan | Contact sales | Premium + usage metrics, user management, centralized billing |
QuillBot Premium’s monthly-billed price is not shown on the captured premium page. The page surfaces a 58%-off promo on annual at capture time. Re-verify before quoting. (source)
StealthZero pricing
| Tier | Annual (per month) | Monthly | Highlights |
|---|---|---|---|
| Free | $0 | $0 | 600 req/mo, 20/day, unlimited words/req on Origin |
| Starter | $7.99/mo | $9.99 | Unlimited Origin + 1,500 advanced/mo, 1 AI Report/mo |
| Pro | $9.99/mo | $19.99 | Unlimited Origin + 3,000 advanced/mo, unlimited detector scans, 2 AI Reports/mo |
| Premium | $23.99/mo | $29.99 | Unlimited all models, 3 AI Reports/mo, 5 Auto Agent credits |
The price-only summary
| Metric | QuillBot | StealthZero |
|---|---|---|
| Cheapest paid (annual) | $8.33/mo Premium | $7.99/mo Starter |
| ”Most popular” pick | Premium $8.33/mo | Pro $9.99/mo |
| Free tier paraphrase / rewrite cap | 125 words/paraphrase | Unlimited words/req on Origin (20 req/day, 600/mo) |
| Free tier humanizer cap | 125 words, 6 uses/day | Same Origin model, 20 req/day, 600/mo |
Within $2/month of each other at the cheapest paid tier. At the Free tier, the difference is per-request words vs per-day requests, QuillBot’s free humanizer caps at 125 words; StealthZero’s Free is request-based at unlimited words per request but capped at 20 requests/day.
How do the features compare?
QuillBot ships 8+ paraphrase modes + 1 humanizer with no published bypass rate; StealthZero ships 5 rewrite models, locked phrases as first-class controls, and the Cohera sub-model at 100% bypass in internal testing. Liang et al. (2023, arXiv:2304.02819) show why pattern-level rewriting (StealthZero’s design) moves detector scores where synonym swaps do not.
We don’t have a methodology to publish numeric accuracy-or-bypass comparisons here. What we can do honestly is map features and quotas side by side, from each vendor’s own published material.
Paraphraser / rewriter
| Capability | QuillBot Premium | StealthZero |
|---|---|---|
| Number of modes / models | 8+ paraphrase modes (Standard, Fluency, Formal, Simple, Creative, Shorten, Expand, custom) | 5 rewrite models (Origin / Sentinel-Lite / Sentinel-Max / F.R.I.D.A.Y / Jarvis with sub-models Homer/Cohera/Max) |
| Tone control | Yes (within modes) | Yes, Origin: 9 purposes × 5 readability levels; Cohera: 6 tones (Professional/Casual/Academic/Creative/Formal/Conversational) |
| Readability control | Implicit via mode | Explicit, High School / University / Doctorate / Journalist / Marketing |
| Locked phrases / protected keywords | Quoted text preserved; not a separate field | Yes, Locked phrases + Protected keywords are first-class UI |
| Strength / variation slider | Synonym slider | Strength (Quality / Balanced / More Human) + temperature slider (0.3–0.95) |
| Long-doc support | Premium: long documents (10k words) | Origin: unlimited words/request; advanced models capped per request |
AI humanizer
QuillBot Premium now includes an AI humanizer. The humanizer is unlimited on Premium and capped at 125 words / 6 uses per day on Free. QuillBot does not publish a numeric bypass-rate or accuracy claim for the humanizer on its homepage or premium page captured 2026-05-28.
StealthZero’s headline output:
- Base humanizer flow: 99% pass rate target. Not a guarantee, a target.
- Cohera sub-model (under Jarvis): 100% bypass rate in internal testing. Per-model claim, not a blanket claim across all five models.
The Cohera number is the strongest claim we make and we’re deliberate about pairing it with “internal testing” rather than treating it as a universal benchmark.
AI detector
| Capability | QuillBot | StealthZero |
|---|---|---|
| Built-in detector | Yes, AI Detector (unlimited on Premium) | Yes, E.D.I.T.H + Sentrio v2 (4 modes) |
| Modes | Single mode | E.D.I.T.H: balanced. Sentrio v2: Standard / Aggressive / Multilingual / Scholar |
| Minimum words | Not stated on premium page | E.D.I.T.H: no minimum. Sentrio v2: 100 words |
| Multi-detector PDF report | No (single-detector output) | Yes, Turnitin parity + GPTZero + Winston + CopyLeaks in one PDF |
| Sentence-level breakdown | Yes | Yes, flagged segments + readability profile + reading-level breakdown |
| Plan limits (paid entry) | Unlimited on Premium | Starter: 1,500 scans/mo; Pro: unlimited (fair-use) |
This is the most material feature gap. StealthZero’s AI Report bundles four detector outputs into one PDF; QuillBot’s detector returns its own score only. The Proof Report is the artifact you keep when someone asks “did you use AI?”
Other suite features
QuillBot includes a plagiarism checker, citation generator, AI summarizer, AI chat, AI image generator, and translator. StealthZero does not. If you want a single bundle that covers all of those, QuillBot is the right product.
StealthZero includes the Jarvis Agent (essay / report / research / complex task packages priced as one-time add-ons) and the AI Writer for document generation. QuillBot does not.
When is QuillBot the right choice?
QuillBot fits four scenarios: you want one tool for everything, Turnitin AI indicator is not in scope, you’ve already learned the QuillBot UI, or you need translator + paraphraser + citation generator in one window. Premium at $8.33/mo annual covers all of those features in a single subscription.
A few realistic scenarios.
You want one tool for everything
If your workflow is paraphrase → grammar check → check for plagiarism → generate citations → translate quotes, QuillBot Premium covers all of that for $8.33/mo annual. Buying the five specialized tools to replicate the suite would cost more.
Turnitin AI indicator is not in scope
Some universities, some industries, some assignments. Plenty of paraphrasing work has nothing to do with AI detectors. If you need to rephrase source material for citation and reduce text-similarity matches, QuillBot’s paraphraser does that job well.
You’ve already learned QuillBot
The UI is mature, the modes are predictable, and the muscle memory matters when you’re working under deadline. Switching tools mid-thesis is a tax. If QuillBot has worked, it’ll keep working.
You need a translator + paraphraser + citation generator in one window
QuillBot’s bundle is genuinely useful for multilingual academic work where you’re paraphrasing English sources, generating citations, and translating quotes.
When is StealthZero the right choice?
StealthZero fits five scenarios: the Turnitin AI Writing indicator is in scope, you need a Proof Report PDF to attach to submission, your draft requires locked phrases for STEM/legal content, you need a Free tier with unlimited words per request (600 req/mo, 20/day cap), or you want multiple rewrite models including Cohera at 100% bypass in internal testing.
Turnitin AI Writing indicator is in scope
This is the single biggest fit signal. Turnitin’s AI indicator scores statistical patterns a pure paraphraser doesn’t change. StealthZero’s humanizer + Cohera model + AI Report workflow targets that indicator directly.
You need a Proof Report to attach to a submission
If a professor, client, or platform has asked you to verify AI-generation status, the multi-detector PDF (Turnitin parity + GPTZero + Winston + CopyLeaks) is the artifact you hand them. StealthZero generates it; QuillBot does not. The Turnitin component is the official Turnitin output your professor would see when running the same paper, verified to 99.999999999% parity in StealthZero’s internal testing.
You need locked phrases or protected keywords
For STEM theses, legal writing, citation-heavy academic work, the ability to mark specific text spans as “do not rewrite” is the difference between a clean rewrite and broken citations. StealthZero’s Rephrase panel exposes both Locked phrases and Protected keywords as first-class controls.
You want a free tier with unlimited words per request
StealthZero Free is 600 requests/month, 20/day, unlimited words per request on Origin. QuillBot Free is 125 words per paraphrase. For longer paragraphs, the request-based model is materially less awkward.
You need a humanizer that ships with multiple rewrite models
Origin for free unlimited work. Sentinel-Lite / Sentinel-Max / F.R.I.D.A.Y for stronger advanced rewrites. Jarvis with Cohera for the 100%-bypass-in-internal-testing tier. If one model doesn’t clear your text, you can switch, without switching products.
The realistic two-tool workflow
The honest answer for many writers is “use both.”
- Draft. Write or generate the source text.
- Paraphrase in QuillBot. Use Premium’s paraphraser for clarity, mode-shift, and to reduce text-similarity matches against indexed sources. Use the citation generator to format your references.
- Humanize in StealthZero. Run the paraphrased output through the Rephrase tool with your locked phrases applied. Pick Origin first; escalate to Cohera if needed.
- Score in StealthZero. Run a multi-detector check using E.D.I.T.H + Sentrio v2 or the AI Report bundle.
- Fix flagged sentences. Per-sentence rephrase on the segments still scoring as AI.
- Export Proof Report. PDF artifact for submission.
- Cite. Citation hygiene is upstream of any tool.
The combined cost at minimum paid plans: QuillBot Premium ($8.33/mo annual) + StealthZero Starter ($7.99/mo annual) = $16.32/mo annual. If that’s too much, drop the QuillBot side and use StealthZero alone, Origin handles paraphrasing-style rewrites natively; you lose the citation generator and plagiarism checker.
What we’re not doing
A few things we’re deliberately leaving off the page:
- No fabricated “QuillBot output” examples. Older drafts of this post included paragraphs labeled “QuillBot output” that weren’t actually generated by QuillBot. Strawmanning a competitor’s output is defamation risk and we won’t do it.
- No bypass-rate or accuracy comparison table without published methodology. Numbers like “QuillBot fails AI detection 78% of the time” circulate in third-party listicles. We don’t have the test rig to publish them.
- No anonymous “users” testimonials. Where we cite an opinion, it’s an operator quote with provenance or a competitor’s own marketing claim with a source link.
Verdict
If you’ve read this far you probably already know which side fits. The short version:
- Choose QuillBot Premium if you want a writing suite and the AI Writing indicator isn’t your bottleneck. $8.33/mo annual, broad bundle, mature product.
- Choose StealthZero if the AI indicator is your bottleneck, you need locked phrases, or you want a multi-detector Proof Report. Free tier is generous; Pro at $9.99/mo annual covers most students and freelancers.
- Use both if you have the budget, paraphrase in QuillBot, humanize in StealthZero, score before submission. Total cost is roughly the price of one Netflix subscription.
To try StealthZero directly without a card: stealthzero.ai/tools/rephrase. Origin model is unlimited on Free.
Related reading:
- Paraphrasing tool guide, the full category breakdown
- Best paraphrasing tools for students, student-specific picks
- AI rewriter tools 2026, broader rewriter market
- Paraphrasing vs AI humanizing, the category distinction, plainly
- Humanize AI text for Turnitin, Turnitin-specific workflow
QuillBot pricing and feature claims captured 2026-05-28 from quillbot.com/premium. StealthZero product specifications are operator-verified. Pricing pages move; verify before citing in a paper.
References
- Liang, W., Yuksekgonul, M., Mao, Y., Wu, E., & Zou, J. (2023). “GPT detectors are biased against non-native English writers.” arXiv:2304.02819. https://arxiv.org/abs/2304.02819
- Sadasivan, V. S., Kumar, A., Balasubramanian, S., Wang, W., & Feizi, S. (2023). “Can AI-Generated Text Be Reliably Detected?” arXiv:2303.11156. https://arxiv.org/abs/2303.11156
- Weber-Wulff, D., Anohina-Naumeca, A., Bjelobaba, S., et al. (2023). “Testing of detection tools for AI-generated text.” International Journal for Educational Integrity, 19(1). https://doi.org/10.1007/s40979-023-00146-z
Frequently Asked Questions
Is StealthZero a QuillBot alternative?
Only partially. QuillBot is a writing suite, paraphraser plus grammar, plagiarism, AI detector, summarizer, citation generator, translator, and an AI humanizer added on. StealthZero is specialized: an AI humanizer plus a two-engine AI detector with multi-detector PDF reports. If you want a single bundle for clarity-paraphrasing and citations, QuillBot fits. If your text faces an AI indicator (Turnitin AI, GPTZero, Originality.ai), a specialized humanizer like StealthZero is the better fit.
Does QuillBot bypass AI detection?
QuillBot now offers an AI humanizer feature on Premium, unlimited words on Premium, 125 words and 6 uses per day on Free. QuillBot does not publish a numeric bypass-rate or accuracy figure for the humanizer on its homepage or premium page captured 2026-05-28. Treat any bypass claim about QuillBot as unverified unless it cites a methodology.
Which is cheaper, StealthZero or QuillBot?
Captured 2026-05-28: QuillBot Premium is $8.33/mo billed annually. StealthZero Starter is $7.99/mo annual; Pro is $9.99/mo annual. The two cheapest paid tiers are within $2/mo of each other. Free tiers differ, QuillBot Free caps paraphrase at 125 words; StealthZero Free is 600 requests/month with unlimited words per request on the Origin model.
Which is better for students?
Depends on what's being checked. For Turnitin similarity only, QuillBot Premium is the conventional pick, it bundles paraphraser, citation generator, and plagiarism checker. For Turnitin's AI Writing indicator, StealthZero's specialized humanizer plus its multi-detector AI Report PDF is the more defensive choice.
Can I use both?
Yes, and many writers do. A common workflow: draft, paraphrase in QuillBot for clarity and similarity reduction, then humanize in StealthZero to clear the AI indicator before submission. Score the final text with a multi-detector report so you have evidence the version you submitted reads as human.
