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The September 2026 results are in: WriteHuman holds #1, and newcomer SupWriter debuts at #5.Read the full analysis →
HumanizerBench

Head to head · September 2026 cycle

StealthBypass vs Undetectable.ai

Undetectable.ai finished 32.4 points ahead of StealthBypass in the September 2026 cycle, 71.75 to 39.38, ranking #6 against #13 in a field of 14. Undetectable.ai scored higher on 4 of 5 detectors and 7 of 7 writing categories. StealthBypass came out ahead on consistency across categories (80.7 vs 71.1) and ZeroGPT (84.4 vs 80.4). The bypass-rate gap, 78.6 to 82.1, sits inside both tools' 95% confidence intervals, so treat bypass as a draw.

39.38 /100
overall score
#13 /14
rank -
+32.37
Undetectable.ai leads →
Detectors
1 4
Categories
0 7
Components
1 4
71.75 /100
overall score
#6 /14
rank ▲ 2
Last tested
Prompts
33
Methodology
v1.2.0

Score components

What the overall score is made of: bypass rate weighs 42%, meaning preservation 32%, readability 16%, consistency across categories 10%. Output-quality penalties come off the total. How scoring works →

Bypass rate CIs overlap Undetectable.ai by 3.5
78.6 82.1
Meaning preservation Undetectable.ai by 42.6
39.5 82.1
Readability Undetectable.ai by 7.7
54.1 61.7
Consistency StealthBypass by 9.6
80.7 71.1
Penalties fewer is better Undetectable.ai by 17.0
−23.0 −6.0

CIs overlap marks a gap that sits inside both tools' published 95% confidence intervals for that component; it may not survive another cycle.

Detector by detector

Share of each tool's outputs that a detector classified as human-written. Undetectable.ai took 4 of 5.

GPTZero Undetectable.ai by 3.1
69.3 72.4
Originality.ai Undetectable.ai by 33.1
58.5 91.7
Copyleaks Undetectable.ai by 9.2
65.1 74.3
Winston AI Undetectable.ai by 22.6
56.3 78.9
ZeroGPT StealthBypass by 4.0
84.4 80.4

Writing categories

Category score per writing context: bypass credit only for real rewrites, blended with the category's own meaning preservation and readability. Small categories swing; the prompt count is shown on each row. How category scores work →

Academic Essay Application Essay Blog Post Business Email Marketing Copy Discussion Board News Article Academic Essay: StealthBypass 39.9 · Undetectable.ai 86.0 Application Essay: StealthBypass 24.5 · Undetectable.ai 73.8 Blog Post: StealthBypass 28.2 · Undetectable.ai 57.5 Business Email: StealthBypass 26.0 · Undetectable.ai 51.0 Marketing Copy: StealthBypass 18.9 · Undetectable.ai 78.4 Discussion Board: StealthBypass 42.8 · Undetectable.ai 78.9 News Article: StealthBypass 35.3 · Undetectable.ai 51.8
StealthBypass Undetectable.ai Outer ring = 100
Academic Essay 6 prompts Undetectable.ai by 46.1
39.9 86.0
Application Essay 6 prompts Undetectable.ai by 49.2
24.5 73.8
Blog Post 6 prompts Undetectable.ai by 29.3
28.2 57.5
Business Email 3 prompts Undetectable.ai by 25.0
26.0 51.0
Marketing Copy 6 prompts Undetectable.ai by 59.5
18.9 78.4
Discussion Board 3 prompts Undetectable.ai by 36.1
42.8 78.9
News Article 3 prompts Undetectable.ai by 16.5
35.3 51.8

Where each one wins

Every measure above that one tool won outright, largest margin first within each group.

StealthBypass

2 wins
  • Consistency Score 80.7 vs 71.1
  • ZeroGPT Detector 84.4 vs 80.4

Undetectable.ai

15 wins
  • Penalties Score −6.0 vs −23.0
  • Meaning preservation Score 82.1 vs 39.5
  • Readability Score 61.7 vs 54.1
  • Bypass rate Score 82.1 vs 78.6
  • Originality.ai Detector 91.7 vs 58.5
  • Winston AI Detector 78.9 vs 56.3
  • Copyleaks Detector 74.3 vs 65.1
  • GPTZero Detector 72.4 vs 69.3
  • Marketing Copy Category 78.4 vs 18.9
  • Application Essay Category 73.8 vs 24.5
  • and 5 more

Questions people ask

Is StealthBypass better than Undetectable.ai?

Undetectable.ai finished 32.4 points ahead of StealthBypass in the September 2026 cycle, 71.75 to 39.38, ranking #6 against #13 in a field of 14. Undetectable.ai scored higher on 4 of 5 detectors and 7 of 7 writing categories. Both tools ran the same 33 prompts, scored by the same 5 detectors, under methodology v1.2.0; every input, output and verdict is published.

Which bypasses AI detectors better, StealthBypass or Undetectable.ai?

Undetectable.ai posted the higher bypass rate, 82.1 vs 78.6, and scored higher on 4 of 5 detectors. StealthBypass led on ZeroGPT; Undetectable.ai led on GPTZero, Originality.ai, Copyleaks and Winston AI. The overall bypass gap is inside both 95% confidence intervals, so it is not a reliable difference.

Do StealthBypass and Undetectable.ai keep the original meaning?

Undetectable.ai preserved meaning better, 82.1 vs 39.5 on our 0–100 similarity scale. On readability, Undetectable.ai rated higher, 61.7 vs 54.1. Penalties this cycle: StealthBypass −23.0, Undetectable.ai −6.0.