We have used every tool on this page on real submissions, not just for the comparison. Below: the criteria we score on, the weights we use, the composite ranking, and a per-tool deep dive. We try to be fair and we own our biases.
How we evaluate
Six criteria, weighted by how much each one tends to matter for the user behaviors we have actually observed. Output quality is weighted highest because it is what the user feels first. Detector pass rate is the second-largest weight because that is the actual job. Privacy gets a floor because we think about it more than most users do, but it gets less weight than the things users see directly.
| Criterion | Weight | What we look at |
|---|---|---|
| Output quality | 30% | Does the humanized prose actually read naturally? Variation in sentence length, removal of signature AI vocabulary, preservation of meaning. |
| Detector pass rate | 25% | Independent testing across Turnitin, GPTZero, Originality.ai, and Copyleaks on a fixed set of AI-generated samples. |
| Free tier value | 15% | What you can actually do without paying. Word limits, signup requirements, watermarks, time gating. |
| UX and speed | 10% | Time from page-load to humanized output, mobile flow quality, copy/paste friction. |
| Pricing transparency | 10% | Are the tiers clear? Do free trials actually free? Are upsells reasonable or aggressive? |
| Privacy posture | 10% | Does the tool retain your text? What does the privacy policy actually say? Where does your input flow? |
Weight breakdown
Composite rankings
Per-criterion scores are 0-10 (10 = best in our test set). Composite is the weighted average, rounded to one decimal. We score Humanize AI on the same rubric as the others using output we generated for testing on the same prompts.
| Tool | Output | Detect | Free | UX | Price | Privacy | Composite |
|---|---|---|---|---|---|---|---|
| Humanize AI | 9.2 | 9.0 | 9.5 | 9.0 | 9.5 | 8.8 | 9.2 ★ |
| Undetectable AI | 8.7 | 8.5 | 6.0 | 8.0 | 7.5 | 7.0 | 7.9 |
| Phrasly | 8.0 | 7.8 | 6.0 | 8.5 | 7.0 | 7.5 | 7.6 |
| HIX Bypass | 8.0 | 7.5 | 5.0 | 7.5 | 6.5 | 7.0 | 7.2 |
| StealthGPT | 7.8 | 7.0 | 4.5 | 7.0 | 7.0 | 7.0 | 6.9 |
| QuillBot | 6.5 | 6.0 | 7.0 | 8.5 | 6.5 | 7.5 | 6.9 |
Per-criterion ranking
Test methodology
For the detector pass rate score we generated 100 test passages: 25 from ChatGPT (mix of GPT-4 and GPT-4o), 25 from Claude (Sonnet and Opus), 25 from Gemini (Pro and Flash), and 25 mixed-source (output from one model rewritten by another). Each passage was 300 to 800 words to land in the reliable detection range. Topics spread across academic essays, blog posts, marketing copy, and business writing.
We ran each passage through each of the six humanizers using their default settings (no fine tuning, no premium-tier features unless they are part of the free product). The humanized output then went through Turnitin AI, GPTZero, Originality.ai, and Copyleaks.
The detector pass rate score reflects how often the humanized output scored "human" or "uncertain" rather than "AI" across all four detectors. We weighted the four detectors equally for this score. Per-tool detector breakdowns are in the individual review pages.
Read the deep dives
Each review page covers what the tool does well, where it falls short, the specific situations where it is the better pick over Humanize AI, and the decision tree for choosing between them.
Undetectable AI
Phrasly
HIX Bypass
StealthGPT
QuillBot
Common questions about these comparisons
Did you really test Humanize AI on the same rubric?
Yes. Same 100 test passages, same default-settings rule, same four detectors. We held our own tool to the same bar. The composite scores in the table are the actual numbers from that run.
Why does the composite score not just say "we win"?
Because it depends on what you weight. Our default weighting (above) reflects the use cases we see most often. If you only care about API access, Undetectable AI's composite would jump. If you only care about Chrome extensions, Phrasly's would. Each individual review page calls out the cases where the competitor wins.
How often do you re-run the tests?
Every quarter, or whenever a major detector updates its model. Detection methodology shifts; rankings shift with it. The dates on each review page show when it was last tested.
Can I see the test passages?
We do not publish the full set because that creates a target detectors and humanizers will train against. We can share a representative sample on request for academic or journalistic review.
What happens if a competitor disputes a score?
We listen. If a vendor can show that a score is wrong (a feature we missed, a tier we tested at the wrong level, an outdated detector version), we update the page and note the change. If the disagreement is about how we weight criteria, that is a methodology disagreement and we explain our weights and stand by them.
Want to understand how detectors work in the first place?
The pillar piece walks through perplexity, burstiness, and signature phrasing. Without that mental model, the composite scores above are just numbers on a page.
Why AI text gets flagged →The fastest comparison is paste it yourself
Open Humanize AI and a competitor side by side. Paste the same draft. Compare the output. Your eyes are the most reliable test we have, and a 30-second test will tell you more than any composite score.
Open the free tool