Your school runs every essay through Turnitin and students normally see the score only after submission. If you want to catch AI-generated phrasing or copied text before you hand work in, several third‑party tools can check the two report types Turnitin produces—AI writing and similarity—and we compared seven of them using each tool’s published prices, limits and test results.
Why you can’t just buy Turnitin
Turnitin does not sell individual licenses or single‑use subscriptions; schools, universities and other organizations buy access and students get it through their institutions. The only Turnitin product available for individual purchase is iThenticate, priced at $125 for a single check up to 25,000 words, and it does not include AI writing detection. Some schools enable Turnitin Draft Coach as an add‑on for Word Online and Google Docs, but it works only through a school account.
What Turnitin checks in your paper
Instructors typically see two reports from Turnitin. The Similarity Report matches your text against web pages, published work and past student papers held by institutions. The AI writing report estimates how much prose reads as machine‑generated. Turnitin says it requires at least 300 words of prose to produce an AI result, and any score from 1% to 19% appears as an asterisk because low scores 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, a figure reported by Campus Technology.
Turnitin Alternatives at a glance
The seven tools we compared focus on AI detection, plagiarism detection, or both. Key facts from published plans and tests:
– Undetectable AI: free AI detector up to 10,000 words, AI Plagiarism Checker showing seven detectors, paid plans from $9.99/month or $5/month billed yearly. Reads 50+ languages; paid plans include unlimited AI detection.
– Scribbr: plagiarism checks in partnership with Turnitin; scans 99 billion web pages and 8 million publications; per‑paper pricing $19.95 up to 7,500 words, $29.95 up to 50,000 words, $39.95 over that. Free AI detector up to 1,200 words.
– GPTZero: free plan with 10,000 words/month; Premium $12.99/month billed yearly or $23.99 month to month, with 300,000 words and a plagiarism check.
– Grammarly: free AI detector with no signup; Grammarly Pro adds a plagiarism checker and costs $12/month billed yearly or $30/month.
– QuillBot: free AI detector in English; Premium $8.33/month billed yearly and adds a plagiarism checker covering 25,000 words/month.
– Copyleaks: bundles AI and plagiarism detection in a Personal plan for $16.99/month or $13.99/month billed yearly; no free plan listed.
– Originality.ai: credit‑based pricing (1 credit = 100 words); AI checks use 1 credit/100 words, AI+plagiarism use 2 credits/100 words. Pro costs $14.95/month or $12.95/month billed yearly and includes 2,000 credits (200,000 words). A limited free plan is available.
Turnitin Alternatives: Undetectable AI — Best for checking AI flags before submission
Undetectable AI’s free detector accepts up to 10,000 words with no signup and highlights each flagged sentence so you can see which lines read as generated. Its AI Plagiarism Checker shows how likely seven well‑known detectors (including GPTZero, Copyleaks, ZeroGPT and Grammarly) are to flag the same text. The site cites a peer‑reviewed study in the Indian Journal of Psychological Medicine that tested 10 free detectors: according to that study, Undetectable AI flagged 100% of an original ChatGPT text and detected rewrites made with QuillBot, Grammarly and ChatGPT at 100%; Sapling was the only other detector in the study to match those results. The detector reads 50+ languages (English gives the most accurate results). Where it’s not a full substitute for Turnitin: neither of these tools matches sentences against published sources, so pair them with a similarity checker such as Scribbr when your draft contains many quotes.
Scribbr — Best for a plagiarism check closest to Turnitin
Scribbr’s plagiarism checker runs in partnership with Turnitin and uses parts of Turnitin’s similarity software and content databases, which Scribbr says include 99 billion web pages and 8 million publications. Scribbr charges per paper: $19.95 up to 7,500 words, $29.95 up to 50,000 words and $39.95 for longer papers. It does not include past student papers stored by schools, so matches against old classmates’ essays may not appear. Scribbr’s free AI detector takes up to 1,200 words per check (English, Spanish, German and French); in the publisher’s review it scored a heavily AI‑edited essay at 0% AI.
GPTZero — Best free monthly allowance
GPTZero’s free plan provides 10,000 words a month. Premium is $12.99/month billed yearly or $23.99 month to month and adds up to 300,000 words and a plagiarism check. Its sentence highlights make flagged lines easy to read; the peer‑reviewed study showed weaker performance on rewritten text, scoring a Grammarly rewrite at 38% AI and a QuillBot rewrite at 29%.
Grammarly — Best if you already pay for it
Grammarly’s AI detector is free and requires no signup. Grammarly Pro adds a plagiarism checker and writing suggestions; pricing is $12/month billed yearly or $30/month. If you already subscribe to Grammarly for grammar and style, Pro gives you both the writing assistant and plagiarism checks in one product.
QuillBot — Best budget pick
QuillBot’s AI detector is free (English only). Premium costs $8.33/month billed yearly and includes a plagiarism checker that covers 25,000 words a month. In the peer‑reviewed study, QuillBot’s detector caught every rewrite tested except the one produced by QuillBot’s own paraphraser, which it scored at 90% AI.
Copyleaks — Best for AI and plagiarism bundled
Copyleaks combines AI detection and plagiarism detection in its Personal plan for $16.99/month or $13.99/month billed yearly; no free plan was listed. Test results were mixed: an in‑house review returned 3 correct calls out of 6 samples with most misses on paraphrased and mixed writing, and the peer‑reviewed study scored the QuillBot rewrite at 0% AI.
Originality.ai — Best for heavy monthly use
Originality.ai uses credits (1 credit = 100 words). An AI check uses 1 credit per 100 words; an AI plus plagiarism check uses 2 credits per 100 words. The Pro plan costs $14.95/month or $12.95/month billed yearly and includes 2,000 credits, equivalent to 200,000 words of AI checks. A limited free plan is available for occasional scans.
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 detectors shakier results. Run a plagiarism or similarity check (for example, Scribbr) and fix any matches that lack quotation marks or proper citation. Run an AI check and examine highlighted sentences rather than relying on the overall score. Rewrite flagged lines in your own words, add original examples or class‑specific details, and keep your version history in Google Docs or Word as the clearest proof you wrote the paper if a score is questioned.
When an outside checker can’t help
No outside tool can give you your exact Turnitin score: each detector uses its own model, and only Turnitin can compare your paper with student papers stored by your school. If your school offers Draft Coach, use it for similarity checks since it runs on Turnitin’s system. Use outside checkers to identify risky sentences early so you can fix them before submission.
Frequently asked questions
Can I use Turnitin without my school? No. Turnitin’s help center says the company doesn’t sell individual licenses. The closest paid product for individuals is iThenticate at $125 per manuscript, which does not include AI detection.
What’s the best free Turnitin alternative? For AI writing, Undetectable AI’s detector checks up to 10,000 words and the AI Plagiarism Checker shows results from seven detectors, both free with no signup. For copied text, Scribbr’s paid plagiarism check is the closest to Turnitin’s databases.
Will another checker give me the same score as Turnitin? Not exactly. Tools use different models and Turnitin hides AI scores between 1% and 19%. Use outside checkers to find sentences most likely to be flagged.
Can Turnitin detect ChatGPT? Turnitin’s AI report is designed to flag text from models like ChatGPT once a paper contains at least 300 words of prose.
What should I do if Turnitin flags my own writing? Ask your instructor to review your version history, outline and notes with you. Turnitin acknowledges false positives and reports a false positive rate under 1% for papers with 20% or more detected AI writing.
If you only run one check before submission, run an AI check first to find machine‑sounding sentences you can rewrite. For quoted or heavily sourced work, add a Scribbr similarity check, then paste the final draft into an AI detector, rework highlighted lines, save your version history and submit.
