Best for Copyleaks
Humanizers ranked by their measured bypass rate against Copyleaks.
An enterprise AI checker and plagiarism-detection platform used by universities, businesses, and content-moderation teams.
| Rank Position by Copyleaks bypass rate on this cycle. Learn more → | Humanizer | Copyleaks Bypass Fraction of samples Copyleaks classified as human-written. Learn more → ↓ | Overall Overall score across all detectors, after penalties. Learn more → | Penalties Total points deducted from the overall score when output-quality issues were detected. Hover a row's chip to see why. Learn more → | Last Tested |
|---|---|---|---|---|---|
| 1 | StealthGPT stealthgpt.ai | 82.8 | 61.52 | −10.0×3Penalties applied
| 1d ago |
| 2 | Stealth Writer stealthwriter.ai | 81.8 | 68.07 | −3.0×2Penalties applied
| 1d ago |
| 3 | Phrasly phrasly.ai | 80.0 | 61.47 | −8.0×3Penalties applied
| 1d ago |
| 4 | Humbot humbot.ai | 78.8 | 66.42 | −1.0Penalties applied
| 1d ago |
| 5 | AI Humanize io aihumanize.io | 72.7 | 59.66 | −10.0×2Penalties applied
| 1d ago |
| 6 | HIX Bypass bypass.hix.ai | 70.4 | 64.84 | None | 1d ago |
| 7 | Undetectable.ai undetectable.ai | 65.6 | 72.17 | −10.0Penalties applied
| 1d ago |
| 8 | WriteHuman writehuman.ai | 61.0 | 73.07 | −1.0Penalties applied
| 1d ago |
| 9 | Walter Writes walterwrites.ai | 58.7 | 62.84 | −8.0×2Penalties applied
| 1d ago |
| 10 | Humanize AI Pro www.humanizeai.pro | 55.5 | 70.49 | None | 1d ago |
| 11 | Super Humanizer superhumanizer.ai | 48.2 | 54.13 | −5.0×3Penalties applied
| 1d ago |
| 12 | Grammarly www.grammarly.com/ai-humanizer | 0.0 | 53.38 | None | 1d ago |
| 13 | NoteGPT notegpt.io/ai-humanizer | 0.0 | 44.04 | None | 1d ago |
Higher bypass rate alone ≠ a better tool. See the balanced overall ranking on the main leaderboard .
How scores are computed
See the full methodology →Overall score formula
- Bypass 42% Share of detector tests where the output was classified as human.
- Meaning 32% How well the output preserves the original meaning.
- Readability 16% How clear, fluent, and natural the writing reads, rated by a language model.
- Consistency 10% How evenly the humanizer performs across writing categories.
Penalties (right) are deducted from the overall score. Final score is clamped at 0.
Possible penalties
| Code | Penalty | Max |
|---|---|---|
| Identical to input The tool returned the input mostly unchanged. No real humanization happened. | −2.0 | −10.0 |
| Refusal The tool refused to humanize the input, often due to a content-policy block. | −1.0 | −10.0 |
| Meaning drift The output's meaning drifted significantly from the original input. | −1.0 | −10.0 |
| Length inflation The output ran much longer than the input, a common trick that pads text to dilute the AI signal. | −1.0 | −10.0 |
| Length deflation The output came back much shorter than the input. The rewrite dropped content instead of paraphrasing it. | −1.0 | −10.0 |
Maximum possible total penalty: −50.0 (off 100).
Top 3 for Copyleaks
- StealthGPT 82.8%
- Stealth Writer 81.8%
- Phrasly 80.0%
Frequently Asked Questions
Which AI humanizer best bypasses Copyleaks?
The top of the ranking on this page is the humanizer with the highest measured bypass rate against Copyleaks in the latest cycle. Bypass rate is the share of test samples Copyleaks classified as human-written after humanization. We re-run this every cycle, so the leader can change month to month — and a tool that tops Copyleaks is not necessarily best overall.
How is the Copyleaks bypass rate measured?
Every humanizer processes the same fixed prompt set, and each output is submitted to Copyleaks. We record the raw verdict for every sample and report the fraction marked human as a 0–100 score. The raw per-sample verdicts are published per cycle in detector-scores.json, so anyone can recompute the number.
Does a high Copyleaks score mean a humanizer is good?
Not on its own. A single detector's bypass rate ignores meaning preservation, readability, and how a tool performs against the other detectors. Use this page to compare Copyleaks specifically, then check the overall leaderboard for the balanced ranking before deciding.