Can AI Detectors Detect Grammarly or QuillBot?
Key takeaways
- Simple grammar and spelling fixes rarely trigger AI detectors on their own.
- Generative rewrite features create AI text, and that can be flagged.
- Paraphrasers like QuillBot change wording, and detectors increasingly look for that.
- Over-editing human writing can smooth away the variation that marks it as human.
AI Humanizer Detector is not affiliated with Grammarly, QuillBot or Turnitin. Product features change frequently; check each tool’s current documentation.
The short answer
Light grammar correction almost never makes human writing look like AI. Generative rewriting and heavy paraphrasing can. The more of a sentence a tool writes for you, the more that sentence takes on the statistical fingerprint of machine text, and the more likely an AI detector is to notice.
Grammarly and AI detection
Grammarly does two very different things, and detectors treat them differently:
| Feature | What it does | Effect on AI detection |
|---|---|---|
| Spelling, grammar and punctuation fixes | Corrects individual errors | Minimal. Your sentences are still yours. |
| Clarity and tone rewrites | Rephrases whole sentences | Moderate. Many accepted rewrites can smooth out natural variation. |
| Generative AI (drafting, “improve it” prompts) | Writes new text with a language model | High. This is AI-generated text and can be detected as such. |
Grammarly also offers features that record how a document was written, which some writers use to show their process if their work is questioned. Keeping version history in Google Docs or Word serves the same purpose.
QuillBot and paraphrasing tools
Paraphrasers rewrite text sentence by sentence. Applied to AI output, they can lower some detector scores, which is why research such as the DIPPER study found paraphrasing so effective against early detectors (see do AI humanizers work?). Detection has since adapted: providers train on paraphrased examples, and Turnitin has described detection aimed specifically at AI text that was modified by paraphrasing tools.
There is also a less obvious risk. Paraphrasing your own writing replaces your word choices with the tool’s, which tend to be the kind of predictable choices detectors associate with AI. Human writing that has been paraphrased can end up scoring higher, not lower.
Why editing tools affect detection scores
AI detectors look for predictability and uniformity (see how AI detectors work). Writing tools are designed to make text more standard: correct, conventional and smooth. A few corrections don’t matter, but when a tool rewrites most sentences, it nudges the text toward exactly the patterns detectors look for, whoever wrote the original.
Using editing tools without false flags
- Accept spelling and grammar fixes freely; they rarely affect detection.
- Be selective with full-sentence rewrites. Keep the ones that genuinely improve clarity and reject the rest.
- Avoid running your own finished writing through a paraphraser.
- If you use generative features, follow your institution’s or employer’s disclosure rules.
- Keep version history so you can show how your document developed.
- Check your final draft with an AI checker, and rewrite any highlighted sentences in your own words.
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