Your school runs every essay through Turnitin, but the first time you see your score is after you’ve already hit submit.
That’s a rough setup if you used ChatGPT to sketch an outline or pulled quotes from a stack of sources the night before. You want to know what the report will say while there’s still time to change the paper.
Turnitin won’t sell you an account, so the next best move is a tool that checks for the same two problems: AI writing and copied text. We’ve compared seven of them using each tool’s published prices, limits and test results.
Why You Can’t Just Buy Turnitin
Turnitin’s help center says the company doesn’t sell individual licenses or single-use subscriptions. Schools, universities and other organizations buy it, and students get access only through them.
The one Turnitin product you can buy yourself is iThenticate, built for researchers checking manuscripts. A single check costs $125 for up to 25,000 words, and it doesn’t include AI writing detection.
Some schools also switch on Turnitin Draft Coach, an add-on for Word Online and Google Docs that runs a similarity check on your draft. It only works through your school account, so ask your library or IT help desk whether you have it.
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What Turnitin Checks in Your Paper
Your instructor usually sees two reports. The Similarity Report matches your text against web pages, published work and past student papers, and the AI writing report estimates how much of your prose reads as machine-generated.
The AI report has rules worth knowing before you test your own draft. Guidance from the University of Georgia explains that Turnitin needs at least 300 words of prose, and any score from 1% to 19% shows up as an asterisk.
Low scores get hidden because they produce more false alarms. Turnitin has also said its false positive rate stays under 1% for documents where it detects 20% or more AI writing, as Campus Technology reported.
Under 1% still means some papers written entirely by students get flagged. A few minutes of checking before you submit is cheap insurance against being one of them.
Turnitin Alternatives at a Glance
| Tool | Checks AI writing | Checks plagiarism | Free option | Paid price |
|---|---|---|---|---|
| Undetectable AI | Yes | AI plagiarism, across 7 detectors | AI Detector and AI Plagiarism Checker, no signup | From $9.99 a month, or $5 a month billed yearly |
| Scribbr | Yes | Yes, in partnership with Turnitin | AI detector up to 1,200 words | $19.95 per plagiarism check up to 7,500 words |
| GPTZero | Yes | Yes, on Premium | 10,000 words a month | $12.99 a month billed yearly |
| Grammarly | Yes | Yes, on Pro | AI detector, no signup | $12 a month billed yearly, $30 monthly |
| QuillBot | Yes | Yes, on Premium | AI detector in English | $8.33 a month billed yearly |
| Copyleaks | Yes | Yes | None listed | $13.99 a month billed yearly, $16.99 monthly |
| Originality.ai | Yes | Yes | Limited free plan | $12.95 a month billed yearly, $14.95 monthly |
1. Undetectable AI: Best for Checking AI Flags Before You Submit
We built our free AI detector for the moment right before you hand something in. You paste up to 10,000 words, skip the signup and get an AI score with every flagged sentence highlighted.
The highlights matter more than the number. They show you which lines read as generated, so you know exactly where to rework the paper in your own words.
Our free AI Plagiarism Checker adds a second view. It shows how likely seven well-known detectors are to flag your text, including GPTZero, Copyleaks, ZeroGPT and Grammarly, all on one screen.
Our strongest outside proof comes from a peer-reviewed study in the Indian Journal of Psychological Medicine that tested 10 free AI detectors. We flagged 100% of the original ChatGPT text as AI.
The researchers then rewrote that text with QuillBot, Grammarly and ChatGPT. We caught all three rewrites at 100%, and Sapling was the only other detector in the study to do the same.
The detector also reads 50+ languages, with English giving the most accurate results. Paid plans start at $9.99 a month, or $5 a month billed yearly, and every plan includes unlimited AI detection.
Where We’re Not the Right Fit
Both of our checkers look for AI writing. Neither one matches your sentences against published sources, so if your paper leans on quotes, pair us with a similarity checker like Scribbr for that half of the Turnitin report.
The study also ran in January 2024 on free versions of each tool. Newer AI models weren’t part of it, so treat it as one strong data point and keep checking your own drafts.
2. Scribbr: Best for a Plagiarism Check Close to Turnitin
Scribbr’s plagiarism checker runs in partnership with Turnitin and uses parts of Turnitin’s similarity software and content databases. Scribbr says it scans 99 billion web pages and 8 million publications.
You pay per paper instead of per month. A check costs $19.95 for up to 7,500 words, $29.95 up to 50,000 words and $39.95 for anything longer, which suits you if you only need it before big deadlines.
The databases Scribbr borrows from Turnitin cover web pages and publications. Past student papers stored by schools aren’t included, so a match against an old classmate’s essay won’t show up.
Scribbr’s free AI detector takes up to 1,200 words per check with no signup, in English, Spanish, German and French. In our Scribbr review, it scored a heavily AI-edited essay at 0% AI.
3. GPTZero: Best Free Monthly Allowance
GPTZero’s free plan gives you 10,000 words a month, enough for a few essays without paying. Premium costs $12.99 a month billed yearly or $23.99 month to month, with 300,000 words and a plagiarism check.
The sentence highlights are easy to read and show exactly which lines look generated. Rewritten text is its weak spot. In the same peer-reviewed study, GPTZero scored the Grammarly rewrite at 38% AI and the QuillBot rewrite at 29%.
We go deeper into its features and limits in our GPTZero review.
4. Grammarly: Best If You Already Pay for It
Grammarly’s AI detector is free and needs no signup. Grammarly Pro adds a plagiarism checker on top of its writing suggestions, and it costs $12 a month billed yearly or $30 month to month.
If you already use Grammarly for grammar, this saves you a second subscription. If all you need is a check before you submit, you’d be paying for a full writing assistant to get it.
5. QuillBot: Best Budget Pick
QuillBot’s AI detector is free and reads English only. Premium costs $8.33 a month billed yearly and adds a plagiarism checker that covers 25,000 words a month.
In the peer-reviewed study, QuillBot’s detector caught every rewrite except the one made with its own paraphraser, which it scored at 90% AI. The 25,000-word cap gets tight if you recheck long papers several times.
6. Copyleaks: Best for AI and Plagiarism in One Plan
Copyleaks bundles AI detection and plagiarism detection in its Personal plan, which costs $16.99 a month or $13.99 a month billed yearly. Its pricing doesn’t list a free plan.
Results were mixed when we tested it. Our Copyleaks review got 3 correct calls out of 6 samples, with most misses on paraphrased and mixed writing, and the peer-reviewed study saw it score the QuillBot rewrite at 0% AI.
7. Originality.ai: Best for Heavy Monthly Use
Originality.ai charges in credits, and 1 credit covers 100 words. An AI check uses 1 credit per 100 words, while an AI plus plagiarism check uses 2.
Pro costs $14.95 a month or $12.95 a month billed yearly and includes 2,000 credits, which is 200,000 words of AI checks. There’s also a free plan for limited use if you only need a scan now and then.
How to Check Your Paper Before You Submit
- Finish the full draft first. Turnitin won’t score AI writing under 300 words, and short chunks give every detector shakier results.
- Run the plagiarism check. Use a similarity checker such as Scribbr and fix any match that’s missing quotation marks or a citation.
- Run the AI check. Paste the same version into our detector and look at which sentences get flagged, beyond the overall score.
- Rewrite flagged sentences in your own words. Add your own examples and details from class, which generic AI text usually lacks.
- Keep your version history. Google Docs and Word both save it, and it’s the clearest proof you wrote the paper if a score gets questioned.
When an Outside Checker Can’t Help
No outside tool can tell you your exact Turnitin score. Each detector runs its own model, and only Turnitin can compare your paper with the student papers your school has stored.
If your school offers Draft Coach, use it for the similarity side, since it runs on Turnitin’s own system. Use outside checkers to find risky sentences early, while you still have time to fix them.
Frequently Asked Questions
Can I use Turnitin without my school?
No. We at Undetectable AI checked Turnitin’s help center, and it states that Turnitin doesn’t sell individual licenses. The closest option is iThenticate at $125 per manuscript, which leaves out AI detection.
What’s the best free Turnitin alternative?
For AI writing, our AI Detector checks up to 10,000 words at a time and our AI Plagiarism Checker shows results from seven detectors, both free with no signup. For copied text, Scribbr’s paid check is the closest match to Turnitin’s databases.
Will another checker give me the same score as Turnitin?
Not exactly. Every tool uses a different model, and Turnitin hides AI scores between 1% and 19%. Use outside checkers to find the sentences most likely to get flagged.
Can Turnitin detect ChatGPT?
Turnitin’s AI report is built to flag text from models like ChatGPT once a paper has at least 300 words of prose. We explain how it works in our guide to Turnitin and ChatGPT.
What should I do if Turnitin flags my own writing?
Ask your instructor to go through your version history, outline and notes with you. Turnitin itself says false positives happen and only reports a rate under 1% for papers with 20% or more detected AI writing.
Conclusion: Our Pick for Checking Your Paper Before Turnitin
If you only run one check before you submit, make it an AI check. That’s the half of a Turnitin report you can’t predict from your own citations, and it’s the one that causes the most stress after you hit submit.
That’s why we put Undetectable AI at No. 1. Our AI Detector shows the exact sentences that read as generated, and our AI Plagiarism Checker shows how seven other detectors are likely to see the same text, both free with no signup.
The outside proof backs it up. In the peer-reviewed test of 10 free detectors, we caught all three rewritten versions of the AI text, which only one other tool managed.
If your paper quotes a lot of sources, add a similarity check from Scribbr before the deadline. Then paste your final draft into our AI Detector, rework the highlighted lines in your own words and submit with your version history saved.