HumanizerEval

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September 2026 review · same 50 texts

Undetectable.ai vs HIX Bypass

In the September 2026 HumanizerEval review, Undetectable.ai and HIX Bypass rewrote the same 50 English texts. Undetectable.ai cleared all 5 detectors on 15 of them; HIX Bypass on 1. The difference is mostly Pangram: on 15 samples Undetectable.ai passed it where HIX Bypass failed, and the reverse never happened. On ZeroGPT and Winston AI the two were close to even.

Per-sample agreement

Per-sample agreement, September 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 4.0Undetectable.ai15 to 0134
GPTZero 2026-09-13-baseUndetectable.ai14 to 0342
Originality.ai turboUndetectable.ai16 to 1312
ZeroGPT defaultTied0 to 0500
Winston AI 5.0Tied1 to 1480
All 5 detectorsUndetectable.ai14 to 0135

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 34 of 50 here.

Quality and output discipline

Quality and output discipline, September 2026.
MeasureUndetectable.aiHIX Bypass
26%18%
28%6%
94%96%
78%66%
1.211.11
70
00
University / General Writing / More Human, v11srLatest
Websiteundetectable.ai hixbypass.com

On per-sample quality scores, Undetectable.ai scored higher on 19 samples, HIX Bypass on 11, and the two tied on 20. HIX Bypass’s output was shorter on 35 of 50 samples; mean length ratios were 1.21 and 1.11, or 21% longer than the input and 11% longer than the input respectively.

Where each one outperforms the other

Undetectable.ai

  • Pangram: passed 16 of 50 against 1, including 15 samples where HIX Bypass failed, against 0 the other way.
  • GPTZero: passed 48 of 50 against 34, including 14 samples where HIX Bypass failed, against 0 the other way.
  • Originality.ai: passed 47 of 50 against 32, including 16 samples where HIX Bypass failed, against 1 the other way.
  • Winston AI: tied at 49 of 50 but on a higher mean human score, 97.5% to 96.4%. It passed 1 sample where HIX Bypass failed.
  • Factual consistency: 26% against 18%.
  • Naturalness: 28% against 6%.
  • Stance preservation: 78% against 66%.

HIX Bypass

  • Originality.ai: passed 1 sample where Undetectable.ai failed, even though it was detected more often overall, passing 32 to 47.
  • ZeroGPT: tied at 50 of 50 but on a higher mean human score, 96.5% to 95.0%. It passed 0 samples where Undetectable.ai failed.
  • Syntax integrity: 96% against 94%.
  • Length: shorter output on 35 of 50 samples, which matters under a word limit.

Undetectable.ai vs HIX Bypass FAQ

Is Undetectable.ai better than HIX Bypass?

In the September 2026 HumanizerEval review, Undetectable.ai cleared all 5 detectors on 15 of the 50 shared samples and HIX Bypass on 1. On ZeroGPT and Winston AI the two were within 6 points of each other. Quality ran 19 samples to 11, with 20 ties.

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

Undetectable.ai. In September 2026, Undetectable.ai passed Pangram on 16 of the 50 shared samples and HIX Bypass on 1. On 15 samples Undetectable.ai passed where HIX Bypass failed; the reverse never happened. Both failed on 34.

Which humanizer changes the text less?

Undetectable.ai. It scored higher on per-sample quality on 19 of 50 samples, against 11. Undetectable.ai’s outputs averaged 1.21× the input length and passed factual consistency on 26%; HIX Bypass’s averaged 1.11× and passed on 18%. On stance preservation the split was 78% to 66%. HIX Bypass produced the shorter output on 35 of 50 samples.

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