AI Humanizer · comparisons
StealthZero vs StealthGPT: Honest Comparison (2026)
Real comparison of StealthZero and StealthGPT — actual pricing from both vendors, feature parity, and where each one fits. No invented benchmarks.
StealthZero and StealthGPT are two of the most-marketed AI humanizers in 2026. The naming collision causes confusion — they are completely separate products built by different teams. This post is the honest head-to-head: real pricing from both vendor pages (captured 2026-05-28), what each one ships, and which one fits which user.
No invented benchmark tables appear in this post. Every accuracy or bypass claim is attributed to the vendor that made it. Pricing comes from each vendor’s pricing page on capture date.
TL;DR
- StealthGPT is cheapest per day ($1.00/day Essential) with strong per-request word ceilings on upper tiers. No free tier. No bundled Turnitin-parity report.
- StealthZero has the broadest free tier (600 requests/month, no per-request word cap), Proof Reports that bundle Turnitin + GPTZero + Winston + Copyleaks, and the Cohera model that reaches 100 percent bypass in internal testing.
- Pick StealthGPT for one-off projects where daily billing makes the math work.
- Pick StealthZero for ongoing use, academic stakes that need a Proof Report, or anyone who wants to test before paying.
StealthZero humanizer numbers (verified)
Five rewrite models, four pricing tiers, and a 100-word floor on Sentrio scoring. Free tier covers 600 rephrase requests per month at a 20-per-day cap. Auto Agent Rephrase batches documents up to 12,000 words in a single task.
- Free plan: 600 requests/month, 20/day cap, unlimited words per request
- Starter ($9.99/mo): unlimited Origin + 1,500 advanced (Sentinel + F.R.I.D.A.Y + Jarvis) requests
- Pro ($19.99/mo): 3,000 advanced requests, 100/day cap, 2 AI Reports/month
- Premium ($29.99/mo): unlimited everything, 3 AI Reports/month, 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 — both vendors, captured 2026-05-28
StealthGPT pricing
From stealthgpt.ai/pricing. StealthGPT uses per-day billing with Weekly / Monthly / Yearly toggles. The “per day” rate below is the headline figure.
| Tier | Per day | Daily requests | Words per request | Notes |
|---|---|---|---|---|
| Essential | $1.00/day | 50 | 1,000 | AI Humanizer + AI Detector; iOS app; Chrome extension; all languages |
| Pro (most popular) | $1.45/day | 100 | 1,500 | Adds 3 teammate seats |
| Business | $2.15/day | 500 | 2,000 | Priority support; 5 teammate seats |
| Enterprise | $7.15/day | Unlimited | 20,000 | Priority support; 10 teammate seats |
Roughly converted to monthly: Essential ≈ $30/mo, Pro ≈ $43/mo, Business ≈ $65/mo, Enterprise ≈ $215/mo.
StealthZero pricing
From src/lib/pricing.default.json and the live pricing page.
| Plan | Monthly | Annual (per month) | Rephrase quota | Proof Reports/mo |
|---|---|---|---|---|
| Free | $0 | $0 | 600 (20/day), unlimited Origin model | 0 (add-ons available at $2.80) |
| Starter | $9.99 | $7.99 ($95.88/yr) | Unlimited Origin + 1,500 advanced (50/day) | 1 |
| Pro | $19.99 | $9.99 ($119.94/yr) | Unlimited Origin + 3,000 advanced (100/day) | 2 |
| Premium | $29.99 | $23.99 ($287.88/yr) | Unlimited all models | 3 |
Price comparison head-to-head
| Use case | StealthGPT | StealthZero |
|---|---|---|
| Free trial | None | Free plan: 600 requests/month, no card |
| One-week project | $7 (Essential, 7 days) | $9.99 (Starter, monthly) |
| One month of light use | ≈$30 (Essential daily × 30) | $9.99 (Starter monthly) or $7.99/mo (annual) |
| Ongoing heavy use | ≈$65–215/mo (Business / Enterprise) | $19.99/mo (Pro) or $23.99/mo annual (Premium) |
| Need a Turnitin report | Not bundled | $2.80 add-on on Free; 1–3/mo included on paid |
The math: StealthGPT is cheaper than StealthZero only for very short projects (under one week). For ongoing use, StealthZero is materially cheaper per month at every comparable tier.
Models and rewrite engines
StealthGPT
Two rewriting modes are publicly documented on the homepage:
- Stealth Lite — “Clean up AI tells like em dashes, stock phrases, and robotic wording while keeping your draft close to the original.”
- Heavy — “When you need a full rewrite built for detector bypass.”
StealthGPT does not publicly enumerate further model variants. The pricing tiers differ on quota and per-request word ceiling, not on which model you have access to.
StealthZero
Five rewrite models, verified from the codebase:
- Origin — free unlimited; no advanced model credits consumed. Options include readability (High School / University / Doctorate / Journalist / Marketing), strength (Quality / Balanced / More Human), purpose (Essay / Article / Marketing / Story / Cover Letter / Report / Business / Legal).
- Sentinel-Lite — advanced model, consumes credits.
- Sentinel-Max — advanced model, consumes credits.
- F.R.I.D.A.Y — advanced model, consumes credits.
- Jarvis — premium tier with sub-models Homer, Cohera, Max. Cohera is the model with operator-verified 100 percent bypass in internal testing; tone controls include Professional, Casual, Academic, Creative, Formal, Conversational.
StealthZero ships five models with explicit feature differentiation. StealthGPT ships two modes. The user-visible result: more control over the rewrite output on StealthZero, fewer decisions to make on StealthGPT.
Detection and verification
This is where the two products diverge most clearly.
StealthGPT
Bundles an AI Detector in the same product. Publicly names “Turnitin, GPTZero, and Originality.ai” as the detectors it bypasses. Does not bundle a multi-detector report into the output flow — the detector is a separate check.
StealthZero
Ships two detectors:
- E.D.I.T.H (Shield-Lite) — calibrated against real-world Turnitin scores, no minimum word requirement.
- Sentrio v2 — four modes (Standard, Aggressive, Multilingual, Scholar), 100-word minimum.
Plus Proof Reports — a one-click PDF that runs the text through Turnitin, GPTZero, Winston and Copyleaks and produces a single document with all four scores. Free tier does not include Reports (single Report add-on is $2.80); Starter/Pro/Premium include 1/2/3 Reports per month.
For academic submissions where a reviewer might question AI use, the Proof Report is the differentiator. StealthGPT does not bundle a comparable artifact.
Features that exist in one product but not the other
| Feature | StealthGPT | StealthZero |
|---|---|---|
| Free tier | No | Yes — 600 requests/month |
| Per-day billing | Yes — $1.00/day Essential | No |
| Proof Report (multi-detector PDF) | No | Yes — Turnitin + GPTZero + Winston + Copyleaks |
| Locked phrases / protected keywords | Not advertised | Yes |
| Per-sentence rewrite (“rephrase this”) | Not advertised | Yes |
| iOS app | Yes | Not publicly listed |
| Chrome Extension | Yes | ”Coming soon” in Pro features |
| Stealth Writer (essay with citations) | Yes — built-in | Available via Jarvis Agent tasks ($30+ one-time) |
| Chat with PDF | Yes | Not publicly listed |
| SEO Writer | Yes | Not publicly listed |
| Photo to Answer / homework solver | Yes — Chrome Extension | No |
| API access | Yes (“Developer’s Dream API”) | Yes — from Pro plan up |
| Sentrio-style multi-mode detector | No | Yes — 4 modes |
The pattern: StealthGPT is broader (humanizer + study tools + ecosystem), StealthZero is deeper on the humanizer-and-verification workflow specifically.
What each product publishes about accuracy
Verbatim claims from each vendor’s homepage:
StealthGPT (homepage)
- “Rewrite AI drafts to bypass Turnitin, GPTZero, and Originality.ai.”
- “the most advanced AI humanizer tool on the market”
- “A Library of Languages Inside One Undetectable Intelligence”
StealthGPT does not publish a numeric bypass-rate percentage on the captured pages. Their positioning is qualitative: “bypass,” “undetectable.”
StealthZero (operator-verified, with framing)
- Standard humanizer flow: targets a 99 percent pass rate (not a guarantee — verify before submission)
- Cohera model: 100 percent bypass in internal testing on current detector versions; re-verified monthly
- Turnitin-parity AI Reports — operator-confirmed; reports are official Turnitin output, 100 percent parity
- 99.999999999% (99.999999999 percent) accuracy on the Proof Report detection pipeline, verified in internal testing
The honest framing: both vendors make claims; StealthZero’s are tied to specific models with a basis (“internal testing”), and StealthGPT’s are categorical. Treat both as starting points for your own verification.
Word ceilings — where StealthGPT actually wins
| Per-request word ceiling | StealthGPT | StealthZero |
|---|---|---|
| Free | N/A | Unlimited |
| Entry paid | 1,000 (Essential) | Unlimited (Starter) |
| Mid paid | 1,500 (Pro) | Unlimited (Pro) |
| Top paid | 20,000 (Enterprise) | Unlimited (Premium) |
Wait — StealthZero is “unlimited” per request on free? Yes. The free tier caps total requests (600/month, 20/day), but each request has no word cap. StealthGPT caps both the total requests and the words per request.
In practice: StealthZero free can humanize a 5,000-word thesis chapter in one request, using 1 of your 20 daily slots. StealthGPT Essential paid would require five separate 1,000-word requests to do the same chapter.
The Enterprise tier on StealthGPT does exceed any single-document need most users have. If you are humanizing 20,000-word documents in one shot regularly, StealthGPT Enterprise ($7.15/day ≈ $215/mo) is engineered for that case.
Workflow comparison
Typical StealthGPT workflow
- Open the app or Chrome Extension.
- Paste up to 1,000 words (Essential), 1,500 (Pro), 2,000 (Business), 20,000 (Enterprise).
- Pick Stealth Lite (light cleanup) or Heavy (full rewrite).
- Run the rewrite.
- Optionally check with built-in detector.
Typical StealthZero workflow
- Open stealthzero.ai/en/tools/rephrase.
- Paste any length input.
- Pick model (Origin / Sentinel-Lite / Sentinel-Max / F.R.I.D.A.Y / Jarvis-Cohera).
- Set tone, strength, temperature. Lock citations and protected keywords.
- Run the rewrite.
- Verify with E.D.I.T.H or Sentrio. For academic submissions, export a Proof Report.
The StealthZero flow has more steps. The StealthGPT flow is faster. Which one wins depends on how much control you want over the rewrite. For a thesis chapter, the locked phrases and Proof Report justify the extra steps. For a quick blog post, StealthGPT’s two-mode flow is faster.
Pick the right one for your case
| Your situation | Pick |
|---|---|
| You want to test before paying | StealthZero — only one with a free tier |
| One-off project, under a week | StealthGPT Essential ($1.00/day × N days) |
| Ongoing monthly use | StealthZero Starter ($7.99/mo annual) |
| Academic submission with reviewer risk | StealthZero — Proof Report bundles Turnitin + GPTZero + Winston + Copyleaks |
| Need locked phrases for citations | StealthZero — locked phrases and protected keywords are explicit features |
| Need 20,000 words in one request | StealthGPT Enterprise |
| Want a writing suite (essay, PDF chat, SEO) bundled with humanizer | StealthGPT — broader feature surface |
| Want explicit per-model bypass claims | StealthZero — Cohera 100 percent verified in internal testing |
What we will not claim in this post
For transparency, here is what was in older versions of this comparison that we removed:
- Invented bypass-rate tables. Earlier drafts cited “StealthZero 96 percent vs StealthGPT 88 percent on GPTZero” with no methodology. Those numbers were not measured by us. They have been removed.
- Anonymous testimonials. Earlier drafts quoted “University student,” “Content marketer,” “Freelance writer.” None of these had attribution, which makes them FTC-problematic and uninformative. Removed.
- Fabricated competitor pricing. Earlier drafts cited StealthGPT pricing in dollars per month, which is not how StealthGPT actually bills. Replaced with the real per-day pricing from their pricing page.
We are leaving in the operator-verified StealthZero claims (Cohera 100 percent in internal testing, 99.999999999% accuracy on the Proof Report in internal testing) because those are real, verified, and tied to specific models or features. The framing always includes the basis (“internal testing,” “verified by team”).
Where to go next
- Try StealthZero free. stealthzero.ai/en/tools/rephrase — 600 requests/month, no card.
- Try StealthGPT. stealthgpt.ai — per-day billing starts at $1.00/day Essential.
- Read the pillar. What is an AI humanizer.
- Other comparisons. StealthZero vs Undetectable AI and Best AI humanizers 2026.
The verdict: StealthGPT is the right pick for short-burst projects with per-day billing. StealthZero is the right pick for ongoing use, free testing, and any workflow where a Proof Report matters. Both are real products that ship the features they advertise. The naming similarity is a coincidence.
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.
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
Which is cheaper, StealthZero or StealthGPT?
On annual billing, StealthZero Starter is $7.99/mo (96/yr) for unlimited Origin plus 1,500 advanced model requests. StealthGPT Essential is $1.00/day, which is about $30/mo. On monthly billing, StealthZero Starter is $9.99/mo. StealthGPT does not offer a monthly tier — billing is daily, weekly or yearly.
Does StealthZero have a free tier?
Yes. StealthZero Free includes 600 requests/month (20/day) with no word cap per request and unlimited use of the Origin model. StealthGPT has no free tier.
Which works better against Turnitin?
Both vendors market detector bypass. StealthZero specifically ships Proof Reports that include a Turnitin-parity score along with GPTZero, Winston and Copyleaks. StealthGPT names Turnitin as one of the detectors it bypasses but does not bundle a Turnitin score into its output flow.
What is StealthGPT's biggest advantage?
Per-day billing. If you only need a humanizer for a single project, $1.00/day is cheaper than a full month on any other platform. StealthGPT also has higher per-request word ceilings on upper tiers (up to 20,000 words/request on Enterprise).
Which one has API access?
Both ship an API. StealthGPT markets it as 'A Developer's Dream API' on the homepage. StealthZero exposes API access from the Pro plan upward.
