Does QuillBot Work as an AI Humanizer? I Tested It

Short answer: no. QuillBot does not work as an AI humanizer.

I tested it myself because people keep recommending it in Reddit threads and YouTube comments. I took a 1,500-word ChatGPT-4o essay, ran it through QuillBot's paraphrase mode at every fluency level, and submitted each version to Turnitin, GPTZero, and Originality.ai.

The best result was 68% AI on Turnitin. The worst was 89%. Not one version passed.

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The test setup

I wanted to be fair. QuillBot has multiple modes (Standard, Fluency, Formal, Simple, Creative, Expand, Shorten), so I tried all of them.

Source text: 1,500 words generated by ChatGPT-4o on "The impact of remote work on employee productivity."

Detectors: Turnitin (institutional), GPTZero (education plan), Originality.ai (publisher plan).

I ran each QuillBot mode twice to check consistency.

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Results by mode

QuillBot Mode	Turnitin	GPTZero	Originality.ai
Standard	82% AI	85% AI	78% AI
Fluency	79% AI	81% AI	74% AI
Formal	85% AI	89% AI	81% AI
Simple	76% AI	78% AI	72% AI
Creative	68% AI	72% AI	65% AI
Expand	84% AI	87% AI	80% AI
Shorten	80% AI	83% AI	77% AI

Creative mode performed "best" at 68% AI on Turnitin. That is still an instant flag. Anything above 20% raises questions. Anything above 50% is treated as AI-generated at most universities.

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Why QuillBot fails at humanization

QuillBot is a paraphrasing tool built for rewording text. That is a different job than humanizing it.

Paraphrasing changes words. It swaps "utilize" for "employ" and "significant" for "substantial." The sentence structure stays the same. The rhythm stays the same. The predictability stays the same.

Humanizing changes patterns. A real humanizer rebuilds how sentences are constructed, varies their length unpredictably, and introduces word choices that are contextually correct but statistically unexpected. That is what detectors measure — not individual vocabulary.

Think of it this way: if someone writes with a very distinctive rhythm — every sentence 15 words, always subject-verb-object, never a fragment or a question — changing the individual words doesn't change the rhythm. Detectors hear the rhythm.

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What about combining QuillBot with manual editing?

I tried that too. I took the Creative mode output (the best-performing version) and spent 20 minutes manually editing it — varying sentences, adding opinions, removing stiff transitions.

Result after manual editing: Turnitin 34%, GPTZero 29%, Originality.ai 31%.

Better, but still dangerous for academic submission. And at that point I'd spent 25 minutes total (5 for QuillBot, 20 for editing) on a result that still might get flagged.

For comparison, running the original ChatGPT text through Humanize AI Pro took 3 seconds and scored 2% on Turnitin. No manual editing needed.

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What QuillBot is actually good for

QuillBot is not bad at what it was designed for. If you need to:

• Rephrase a sentence to avoid self-plagiarism
• Simplify complex academic language
• Reword a quote for paraphrasing in a paper
• Tighten wordy writing

It does those things fine. It just does not humanize AI text, and marketing it (or thinking of it) as an AI humanizer will get you caught.

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Bottom line

QuillBot fails as an AI humanizer because it only changes surface-level vocabulary, not the statistical patterns that detectors measure. Best result in testing: 68% AI on Turnitin (Creative mode). If you need to pass AI detection, use a dedicated humanizer that restructures text at the pattern level. Humanize AI Pro scored 2% on the same text, for free.