QuillBot takes a passage. We take the file. That is the difference you can actually check.
Both categories rewrite sentences, ours included. What separates them is how much of your text the tool has in front of it when it decides what to change, and how much work the output still needs before you can hand it in.
Competitor details verified 2026-08-01. Their own site is the authority.
The short answer
QuillBot is built around a text box: you paste a passage, you get text back, you paste it into your own document. HumanPen is built around the file: a document goes in, a document comes out, and a detection report can name which paragraphs are in scope before anything runs. Which one produces a lower Turnitin score is not something either of us can tell you in a form you could check - Turnitin declines to name the tools its detector was trained against. The four differences below you can read off either product's own pages in a couple of minutes.
When to use QuillBot
- You want paraphrasing itself: say something more clearly, avoid repeating a phrase, split a sentence that got away from you. It is fast, generously free, and good at that.
- You are holding a passage rather than a document - a paragraph of an abstract, a sentence in an email. The box is the shorter route and a file tool buys you nothing.
- Your document has nothing to lose on a plain-text round trip: no footnote markers, no reference-manager citation fields, no table of contents, no tracked changes, no tables. A three-page essay with none of those survives copy-paste intact.
- You want a grammar and fluency check while you are in there. We do not do that at all.
Four things that actually differ
What you hand it, and what comes back. A box takes characters and returns characters, so anything in your document that is not characters has to survive being pasted over. In rough order of how often it bites: footnote and endnote markers, which look like superscript numbers and are not; citation fields inserted by a reference manager, which stop updating the moment they become plain text; cross-references and a table of contents, which are instructions that recompute rather than text that sits there; tracked changes and comment anchors, which have no plain-text form at all; and table cell boundaries, which turn into tabs or into nothing. A file goes in and a file comes out, so none of that lands on your list afterwards.
Who decides which words change. A box has one input and treats all of it the same way - it cannot tell the sentence a report marked from the sentence next to it, because it was never told there was a report. We take a Turnitin or iThenticate AI Writing Report and work only on the passages it names, and you see that scope before anything runs. That is a property of the interface, not a judgement about the rewriting.
The smallest thing the tool will alter. For a box, a sentence or less. For us, a paragraph - our pricing FAQ puts it plainly: a selection is expanded to full paragraphs before it is counted, so the unit drives the bill as well as the result. Whatever a product page says here, believe the number rather than the adjective.
One thing worth watching on academic text whichever you use: terminology. "Significant difference" means something specific in a results section, and a rewrite to "big gap" reads more naturally while being wrong. Read the output for terms and numbers before you read it for style. And our own limits, because they are the reason a lot of people on this page should not buy from us: English only, academic documents only, a file upload required, no unlimited free tier. For a sentence or two we are far too heavy.
FAQ
Will running it through QuillBot lower my AI score?
Neither of us can answer that honestly. Turnitin scores overlapping groups of sentences rather than single sentences, and its own FAQ declines to name the tools its detector was trained against - so any figure quoted at you, by them or by us or by a review site, is unverifiable. Try it on your own text and check against a report you trust.
Would running it several times help?
Each pass is another chance for a term to drift - "significant" to "notable", a defined construct to a near-synonym - and the drift accumulates in a direction nobody checked. If you do run several passes, diff the result against your original and read the terminology before you read the flow.
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?
If the text went through a box, it came back as plain text, so whatever fields it had are already gone and we would be working on the flattened version. Upload the original file instead. If you have already pasted, diff against the original first so you at least know what changed.
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