Turnitin and QuillBot do opposite jobs. Turnitin is an institutional service schools use to check submitted work for matching text and possible AI writing. QuillBot is a writing tool best known for its paraphraser, which rewrites sentences in different words. Because one checks text and the other rewrites it, students often wonder how the two interact.
The honest answer: paraphrasing doesn't remove the need to cite, and rewriting tools can create problems of their own under AI policies.
Disclosure: ZeroTell publishes this blog and makes competing tools, including a paraphrasing tool and a plagiarism checker. We describe Turnitin and QuillBot from publicly available information.
Side by side
| Turnitin | QuillBot | |
|---|---|---|
| Who it's for | Schools, universities, publishers | Students and writers |
| Main purpose | Check submissions for originality and AI writing | Rewrite, summarize and polish text |
| How you get it | Through your institution | Sign up directly; free and paid tiers |
| Plagiarism check | Core feature, includes student-paper databases | Offered as an additional tool; check current details |
| AI detection | Offered to institutions | Has offered an AI detector; check current details |
| Paraphrasing | No | Core feature, with several rewriting modes |
| Other tools | Feedback and grading tools for instructors | Grammar checker, summarizer, citation generator and more |
What Turnitin does
Turnitin compares a submission against web pages, published content and a large database of student papers, then produces a similarity report showing matching passages and their sources. Instructors read that report to decide whether matches are properly quoted and cited or whether something needs a closer look.
Many institutions also enable Turnitin's AI writing indicator, which estimates how much of a submission may be AI-generated. Turnitin has acknowledged that false positives can occur and advises against using the indicator alone to make decisions. Turnitin is sold to institutions, so students usually only see it when submitting assignments.
What QuillBot does
QuillBot's paraphraser takes a sentence or paragraph and rewrites it, with modes that make the result more formal, simpler, shorter or more creative. Around that core, QuillBot has built a suite of writing tools such as a grammar checker, summarizer and citation generator, and it has offered plagiarism and AI detection tools as well. Feature sets and limits change, so check QuillBot's site for current details.
Used well, a paraphraser can help you see a clumsy sentence of your own from a new angle. Used badly, it becomes a way to disguise someone else's work, and that's where it collides with Turnitin.
The real question: what does paraphrasing change?
Many students treat paraphrasing as the opposite of plagiarism. It isn't.
Plagiarism means presenting someone else's words or ideas as your own. Changing the words removes the first problem, matching wording, but not the second. If a paragraph's argument, structure and evidence come from a source, it needs a citation however differently the sentences are phrased.
That's why "rewording until the similarity score drops" misses the point. Even if the matching text disappears from a report, an instructor who knows the source can still recognize the argument. And a paraphrase without a citation is a clearer case of plagiarism than a quote without quotation marks, because it looks like deliberate concealment.
How paraphrasing tools interact with AI detection
There's a second issue. When a tool rewrites text, the result is machine-produced. An AI writing indicator may respond to that, especially if large parts of a document were rewritten. That has two consequences:
- Policy. Some courses treat heavy use of AI paraphrasing tools as AI use. If your policy restricts AI, a paraphraser may fall under it.
- False signals. If you paraphrase your own writing heavily with a tool, your work may look more machine-like than it really is. That can lead to awkward conversations, even though you wrote the original ideas.
Detection is probabilistic, so neither outcome is certain. But it's a good reason to use rewriting tools lightly and to keep your drafts.
When paraphrasing tools are genuinely useful
Paraphrasers aren't inherently dishonest. They help with:
- Unsticking a sentence you wrote. Seeing two or three alternative phrasings can show you a clearer structure.
- Varying repetitive wording. If you've used the same verb five times in a paragraph, a suggestion can help.
- Learning paraphrase technique. Compare a tool's rewrite with your own and notice which one keeps the meaning more precisely.
- Simplifying your own dense text for a different audience, such as a summary for non-specialists.
In each case, the ideas and the original sentence are yours, or the source is cited.
AI ParaphraserReword text in several modesHow to paraphrase a source properly
Whether you use a tool or not, good paraphrasing follows the same steps:
- Read the passage until you understand it. If you can't explain it without looking, you're not ready to paraphrase.
- Close the source and write from memory. Use your own sentence structure, not the original's.
- Compare with the original. Make sure you kept the meaning and didn't borrow distinctive phrases. Put any phrase you kept in quotation marks.
- Add the citation. Use the style your course requires, such as APA, MLA or Chicago.
- Connect it to your argument. A paraphrase should support your point, not replace it.
Here's a short illustration with an invented source sentence:
Original: "Urban tree cover lowers summer street temperatures, which in turn reduces how much electricity nearby buildings use for cooling."
Weak paraphrase (no citation): Tree cover in cities lowers street temperatures in summer, which reduces the electricity buildings nearby use for cooling.
Better paraphrase: Shade from city trees keeps streets cooler in hot months, so the buildings around them need less power for air conditioning (Author, Year).
The weak version only swaps a few words and keeps the original's structure. It also has no citation, so it's plagiarism in two ways. The better version restructures the idea in the writer's own words and credits the source.
Our guide on how to reduce similarity on Turnitin explains how quotes, citations and common phrases show up in a similarity report.
Checking your own work before submission
If your instructor doesn't let you see the Turnitin report before the deadline, a self-check can still catch problems. A web plagiarism checker can find passages that overlap with online sources so you can add missing citations. It won't see Turnitin's student-paper database, so it can't predict your exact score, but it helps with the most common mistake: forgetting where an idea came from.
Common misconceptions
| Belief | Reality |
|---|---|
| "A low similarity score means no plagiarism." | Uncited paraphrased ideas can still be plagiarism. |
| "A high score means I plagiarized." | Quotes, references and common phrases add to the score. Instructors read the matches. |
| "Paraphrasing tools make text original." | They change wording, not authorship of ideas. |
| "Turnitin detects QuillBot specifically." | It doesn't detect brands. It looks at matching text and AI-writing patterns. |
| "If it's not flagged, it's fine." | Instructors read your work. A checker is one tool, not the final judge. |
Which should you use?
You don't choose between Turnitin and QuillBot. If your school uses Turnitin, you'll meet it when you submit. Whether you use QuillBot or any paraphraser while writing is a separate decision that depends on your course's AI policy and your own goals.
If you do use one, use it on your own sentences, keep the citations for anything you borrowed, and keep your drafts.
Key takeaways
- Turnitin checks submitted work for institutions; QuillBot rewrites and polishes text for writers.
- Paraphrasing changes words, not the origin of ideas. Cite your sources either way.
- Heavy AI paraphrasing may fall under AI policies and may look machine-generated to detectors.
- Paraphrasers are useful for improving your own sentences and learning technique.
- Self-check with a plagiarism tool to catch missing citations, not to chase a score.