Head to head · September 2026 cycle
Penlify vs Undetectable.ai
Undetectable.ai finished 35.2 points ahead of Penlify in the September 2026 cycle, 71.75 to 36.57, ranking #6 against #14 in a field of 14. Undetectable.ai scored higher on 5 of 5 detectors and 7 of 7 writing categories. Penlify came out ahead on consistency across categories (100.0 vs 71.1), readability (71.8 vs 61.7) and penalties (−5.0 vs −6.0).
- Detectors
- 0 – 5
- Categories
- 0 – 7
- Components
- 3 – 2
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 →
Detector by detector
Share of each tool's outputs that a detector classified as human-written. Undetectable.ai took 5 of 5.
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 →
Where each one wins
Every measure above that one tool won outright, largest margin first within each group.
Penlify
3 wins- Consistency Score 100.0 vs 71.1
- Readability Score 71.8 vs 61.7
- Penalties Score −5.0 vs −6.0
Undetectable.ai
14 wins- Bypass rate Score 82.1 vs 0.0
- Meaning preservation Score 82.1 vs 62.7
- Originality.ai Detector 91.7 vs 0.0
- Winston AI Detector 78.9 vs 0.4
- Copyleaks Detector 74.3 vs 0.0
- GPTZero Detector 72.4 vs 0.0
- ZeroGPT Detector 80.4 vs 43.0
- Academic Essay Category 86.0 vs 27.0
- Discussion Board Category 78.9 vs 32.1
- Marketing Copy Category 78.4 vs 38.8
- and 4 more
Questions people ask
Is Penlify better than Undetectable.ai?
Undetectable.ai finished 35.2 points ahead of Penlify in the September 2026 cycle, 71.75 to 36.57, ranking #6 against #14 in a field of 14. Undetectable.ai scored higher on 5 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, Penlify or Undetectable.ai?
Undetectable.ai posted the higher bypass rate, 82.1 vs 0.0, and scored higher on 5 of 5 detectors. Undetectable.ai led on GPTZero, Originality.ai, Copyleaks, Winston AI and ZeroGPT.
Do Penlify and Undetectable.ai keep the original meaning?
Undetectable.ai preserved meaning better, 82.1 vs 62.7 on our 0–100 similarity scale. On readability, Penlify rated higher, 71.8 vs 61.7. Penalties this cycle: Penlify −5.0, Undetectable.ai −6.0.