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October 2026 review · same 50 texts

Undetectable.ai vs Phrasly

In the October 2026 HumanizerEval review, Undetectable.ai and Phrasly rewrote the same 50 English texts. Undetectable.ai cleared all 6 detectors on 1 of them; Phrasly on 0. The difference is mostly GPTZero: on 21 samples Undetectable.ai passed it where Phrasly failed, and the reverse never happened. On Originality.ai 5.0 the two were close to even.

Per-sample agreement

Per-sample agreement, October 2026. Counts are out of the 50 shared samples, computed at the 50% human-score threshold. Margin counts the samples only one tool passed, higher count first.
DetectorPassed more oftenMarginBoth passedNeither passed
Pangram 4.1Undetectable.ai18 to 0230
GPTZero 2026-10-07-baseUndetectable.ai21 to 0227
Originality.ai TurboUndetectable.ai14 to 1350
Originality.ai 5.0 model-5.0Undetectable.ai2 to 0048
ZeroGPT defaultUndetectable.ai9 to 0410
Winston AI 5.0Undetectable.ai5 to 0450
All 6 detectorsUndetectable.ai1 to 0049

Every count is computed from scores.csv at build time, not transcribed. “Neither passed” counts the texts that defeated both tools; on Pangram that was 30 of 50 here.

Quality and output discipline

Quality and output discipline, October 2026.
MeasureUndetectable.aiPhrasly
32%50%
28%70%
90%98%
60%84%
1.271.10
110
00
University / General Writing / More Human, v11srStandard model, API default (Phrasly Ultra not enabled on the account)
Websiteundetectable.ai phrasly.ai

On per-sample quality scores, Undetectable.ai scored higher on 5 samples, Phrasly on 33, and the two tied on 12. Phrasly’s output was shorter on 47 of 50 samples; mean length ratios were 1.27 and 1.10, or 27% longer than the input and 10% longer than the input respectively.

Where each one outperforms the other

Undetectable.ai

  • Pangram: passed 20 of 50 against 2, including 18 samples where Phrasly failed, against 0 the other way.
  • GPTZero: passed 43 of 50 against 22, including 21 samples where Phrasly failed, against 0 the other way.
  • Originality.ai Turbo: passed 49 of 50 against 36, including 14 samples where Phrasly failed, against 1 the other way.
  • Originality.ai 5.0: passed 2 of 50 against 0, including 2 samples where Phrasly failed, against 0 the other way.
  • ZeroGPT: passed 50 of 50 against 41, including 9 samples where Phrasly failed, against 0 the other way.
  • Winston AI: passed 50 of 50 against 45, including 5 samples where Phrasly failed, against 0 the other way.

Phrasly

  • Originality.ai Turbo: passed 1 sample where Undetectable.ai failed, even though it was detected more often overall, passing 36 to 49.
  • Factual consistency: 50% against 32%.
  • Naturalness: 70% against 28%.
  • Syntax integrity: 98% against 90%.
  • Stance preservation: 84% against 60%.
  • Length: shorter output on 47 of 50 samples, which matters under a word limit.

Undetectable.ai vs Phrasly FAQ

Is Undetectable.ai better than Phrasly?

In the October 2026 HumanizerEval review, Undetectable.ai cleared all 6 detectors on 1 of the 50 shared samples and Phrasly on 0. On Originality.ai 5.0 the two were within 6 points of each other. Quality ran 5 samples to 33, with 12 ties.

Which humanizer is best for Pangram, Undetectable.ai or Phrasly?

Undetectable.ai. In October 2026, Undetectable.ai passed Pangram on 20 of the 50 shared samples and Phrasly on 2. On 18 samples Undetectable.ai passed where Phrasly failed; the reverse never happened. Both failed on 30.

Which humanizer changes the text less?

Phrasly. It scored higher on per-sample quality on 33 of 50 samples, against 5. Undetectable.ai’s outputs averaged 1.27× the input length and passed factual consistency on 32%; Phrasly’s averaged 1.10× and passed on 50%. On stance preservation the split was 60% to 84%. Phrasly produced the shorter output on 47 of 50 samples.

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