What is the best plagiarism checker in 2026?

Quetext comes up in almost every student thread about free checkers, and for good reason. Its free plan checks both plagiarism and AI, up to 1,000 words. A three-page essay or a blog post fits in one go. No trial clock, no card on file.

Past that, you need a subscription. Essential starts at $14.99 a month and covers 100,000 words a month, with batch uploads of up to 20 files. Professional starts at $29.98 a month for 200,000 words, 100-file batches and unlimited users (they ask you to get in touch past 150). You can pay monthly or yearly, and buy extra words if you go over.

Here's the math that makes it our top pick: one month of Essential checks a 15,000-word thesis six times over. If you write in chapters and want to check each one as you finish it, nothing else in this list is that flexible for the price. Just cancel once the paper is in.

The limit: Quetext mostly compares your text against the web and public content. It doesn't sell access to a scholarly database on the scale of Scribbr's, and it can't see other students' papers. For a paper heavy on journal citations, use it while drafting, not as your final check.

Tip: on the free plan, split a long paper into 1,000-word blocks and start with the sections where you quoted the most. That's where matches pile up.

Scribbr sells one thing: a check, paid per document. You pay by length, get a full report, and that's it. No credits ticking down, no renewal email. A paper up to 7,499 words costs $19.95; longer documents move up to the next price tier.

Its strength is the database. Scribbr says it compares your text against about 99.3 billion web pages and 8 million publications from more than 1,700 academic publishers, including Springer, IEEE and Elsevier. If your paper leans on journal articles, that's where the matches hide that free tools never see. Scribbr describes its technology as similar to what universities use, without promising the same result.

And it's upfront about the gap. Its own FAQ says it has no access to universities' private databases of student papers. If a classmate turned in something close to yours last semester, only your school's tool will catch it. Scribbr does offer a self-plagiarism check: upload your past work and it compares the new paper against it. Handy if you're reusing a chapter.

The limit: every check is billed. Fix your paper and want a second report? You pay again. The free check only shows a breakdown by source category, from 300 words, without the exact passages. Scribbr handles 20 languages and returns a report in 1 to 10 minutes.

Tip: use a cheaper tool while you draft, and save Scribbr for a single check on the version you're actually turning in.

Grammarly is a writing assistant first. The plagiarism checker is a Pro feature: the free version doesn't have it. So if you already pay for Grammarly, you've got a plagiarism checker at no extra cost. If plagiarism is all you need, it's not the most logical purchase.

Grammarly compares your text against roughly 16 billion web pages and ProQuest's academic databases. You run the check from the editor, on the draft you're writing, and matches show up next to the style suggestions. Pro starts at $12 a month; Enterprise is priced on request for teams.

For web content, it does the job well. You see right away when a sentence in your post mirrors a competitor's page word for word. That's the ground where it earns its spot in this ranking.

The limit: paraphrasing. A passage reworded with a few synonyms often slips through. It also flags common phrases as matches, which nudges the score up. And it can't see paywalled journals or theses, so for a thesis it doesn't replace Scribbr or iThenticate.

Tip: run the plagiarism check once the piece is finished, not mid-draft. Style suggestions change your sentences, and an early check no longer matches the final text.

Originality.ai isn't built for students. It's built for people who buy words: a site publishing twenty posts a month, an agency managing freelancers. Plagiarism and AI run in the same scan, so you review a draft once instead of twice.

Pricing is in credits. One credit covers 100 words for a single check; plagiarism plus AI costs 2 credits per 100 words. Pro, at $14.95 a month ($12.95 billed annually), gives you 2,000 credits: 200,000 words of a single check, or 100,000 words with both. A 15,000-word document uses 150 credits for plagiarism alone, 300 with AI. Enterprise runs $179 a month, or $136.58 billed annually.

For a publisher, the math is quick. 100,000 words is about 66 articles of 1,500 words, each checked for plagiarism and AI, every month. There's also a pay-as-you-go option whose credits last 2 years, useful if your volume swings.

The limit: subscription credits expire at the end of each month. A slow month still costs you the full plan. And the AI score, like every AI detector's, gets it wrong sometimes. Don't reject a writer on that number alone. For a thesis, its web-first database adds little over Scribbr.

Tip: run plagiarism only when a draft comes in (1 credit per 100 words), and keep the combined check for the drafts that look off. You cut your credit use in half.

iThenticate is owned by Turnitin, and it's the only way into Turnitin's technology if you don't have a school account. Journals run incoming manuscripts through it. Checking your paper with the same tool before you submit means catching the matches that could get you desk-rejected.

The individual plan is sold per manuscript: $125 for one document up to 25,000 words, $300 for three manuscripts or 75,000 words. Purchases last 12 months and include 5 revisions, so you can fix your text and rerun the check without paying again. Of the six tools here, it's the only one where a re-check after edits is included in the price.

Its database is the strongest for research: journal articles, conference proceedings, scholarly content that consumer tools don't index. The report is precise and assumes you know citation rules.

The limit: price. $125 for a master's thesis is about six times Scribbr's entry tier. And the individual plan doesn't detect AI. If you're a student, ask first whether your school has turned on Draft Coach, Turnitin's add-in for Word and Google Docs: it's free to you when the school has it, and your drafts don't go into the repository.

Tip: bundle your manuscripts. The $300 pack covers three papers or 75,000 words over a year, which brings it to $100 a paper instead of $125.

Copyscape answers a different question from the rest of this list. Not "did I copy someone?" but "did someone copy me?" Paste a URL or a block of text and it searches the web for pages that carry the same content. Site owners use it to find scrapers and to vet articles before publishing.

Premium is pay as you go, and it's cheap. A search costs 3 cents for up to 200 words, plus 1 cent for every extra 100 words. A 1,500-word blog post costs 16 cents. Even a 15,000-word document comes to $1.51. Nothing to subscribe to and nothing that expires at month end.

That price comes with a narrow scope. Copyscape only compares against the open web. No journals, no student papers, no AI detection. For a thesis, it says almost nothing useful.

The limit, beyond coverage: the report is basic. You get a list of matching pages and the overlapping text, not a polished, source-by-source report you'd hand to a professor. Copysentry, the monitoring add-on that watches your pages over time, has its own pricing.

Tip: check every freelance article in Copyscape before it goes live. At 16 cents a post, it's the cheapest insurance against publishing content that already ranks somewhere else.