You ran it through QuillBot and the AI score did not move. You did not use it wrong.
This is the most common experience in the category, and the reason is mechanical rather than a matter of trying harder.
Competitor details verified 2026-08-01. Their own site is the authority.
The short answer
QuillBot is a paraphraser: its job is to say a sentence a different way. AI detectors look primarily not at word choice but at sentence structure and rhythm - and synonym substitution leaves the original skeleton intact. The two tools solve different problems.
When to use QuillBot
- You want paraphrasing itself: express something more clearly, avoid repeating a phrase, break up a long sentence. It is good at this, fast, and generously free.
- You are studying language or practising writing and want to see alternative phrasings.
- You want a quick grammar and fluency check.
- If your goal has nothing to do with AI detection, QuillBot is a good tool and there is no reason to switch.
What detectors actually measure
AI detectors key mainly on sentence-level statistical regularities: whether sentence lengths are unusually even, whether clause structures repeat, whether every paragraph unfolds the same way, whether word choices sit too close to the median. Human writing is uneven - long sentences and short ones, carefully built clauses next to something tossed off. AI output is even and smooth.
Synonym substitution changes the lexical layer: "important" becomes "crucial", "shows" becomes "demonstrates". But sentence length, clause nesting, and paragraph logic - the statistical features - are untouched. The detector sees the same thing it saw before.
For academic text there is a second problem: terminology damage. "significant difference" has a specific meaning in a statistical context; swapped for "big gap" the sentence reads more naturally and is now academically wrong. This failure mode is very common in paraphraser output.
What actually works is semantic-level restructuring: understanding what the sentence says, then re-expressing it with different structure while locking terminology, data, and citations in place. That said, HumanPen only handles academic documents, only supports English, requires a file upload, and has no unlimited free tier. If you just want to rework a sentence or two, we are far too heavy.
FAQ
Does QuillBot have no effect on AI scores at all?
Not none - small edits can move some detectors slightly. But because the sentence skeleton survives, it is usually not enough to change the verdict, which is why so many people report rewriting thoroughly and seeing no change.
Would running it several times help?
Repeated synonym substitution mainly degrades terminology accuracy while leaving sentence structure as it was. On academic text the risk outweighs the benefit.
Are you connected to QuillBot’s AI detector?
No. We do not operate any detector and are not affiliated with one. We support importing Turnitin and iThenticate reports to locate passages that need work.
Should I use QuillBot first, then you?
We would not recommend it. A paraphraser may already have damaged terminology and citation formatting, so we would be working on a degraded text. Process the original.
The only comparison that settles it is your own document
New accounts get 100 credits - enough to run a full section of your own writing through and judge the result yourself.
Try it on your document