| QuillBot Humanizer | Undetectable AI | |
|---|---|---|
| Starting price | $8.33/mo | $9.99/mo |
| Free tier | 125 words | 250 words |
| Bundled detector | Yes | Yes |
| Founded | 2017 | 2022 |
| Best for | People who already pay for QuillBot's grammar/paraphrase suite and want a decent bonus feature, not a dedicated bypass tool. | Teams that want one tool to both check and rewrite content across multiple AI models. |
Price: QuillBot Humanizer is cheaper to start, at $8.33/mo vs $9.99/mo.
QuillBot Humanizer: $8.33/mo billed annually, $19.95/mo monthly. Free tier: 125 words, 6 uses/day.
Undetectable AI: $9.99/mo for the entry tier; higher tiers scale by word volume.
Free tier: Undetectable AI offers a more generous free tier (250 words).
If you just want to test either tool before paying, Undetectable AI's 250-word allowance gives you more room to evaluate quality.
Detection performance
QuillBot Humanizer: Consistently ranks behind dedicated humanizers on Turnitin and GPTZero in third-party comparisons because it leans on synonym substitution rather than deep sentence restructuring.
Undetectable AI: Frequently cited as a top-tier performer against GPTZero and Originality.ai, though results vary by source text length and topic.
AI detector included: QuillBot Humanizer bundles a built-in detector; both both include one.
Strengths at a glance
QuillBot Humanizer
- Bundled AI detector, grammar checker, and paraphraser in one subscription
- Fast — results in under 5 seconds for short passages
- Color-coded change tracking so you can see exactly what was rewritten
Undetectable AI
- Runs output against multiple detector models before returning it
- Supports long-document processing without manual chunking
- Adjustable readability and purpose settings (story, essay, article, email)
Our verdict
Choose QuillBot Humanizer if: people who already pay for quillbot's grammar/paraphrase suite and want a decent bonus feature, not a dedicated bypass tool. Choose Undetectable AI if: teams that want one tool to both check and rewrite content across multiple ai models.
Full QuillBot Humanizer review → · Full Undetectable AI review →