PlagiarismCheck.org is a similarity checking platform sold two ways: pay per page to individuals, and by quote to institutions who want it wired into their LMS. An AI detector does not replace either. Work out which half you use before you compare anything.
Paste some text or load the example to estimate AI likelihood.
Read from plagiarismcheck.org on 16 August 2026. The footer carries a copyright line running from 2015 to 2026, and the about page states the service was created in 2011.
| Component | What the site states |
|---|---|
| Core product | Plagiarism checking with reports showing matching sources by type and similarity percentage |
| AI checking | TraceGPT, sold as part of the same account |
| Authorship | Fingerprint Authorship Verification |
| Writing tools | Grammar Checker, Citation Generator, Essay Grader, Topic Generator |
| Access points | Web app, Google Docs Add-on, Chrome extension |
| LMS integrations | Canvas, Moodle, Google Classroom, Blackboard, Brightspace, Schoology, Populi |
| Developer | A plagiarism check API with its own documentation |
| Institutional tiers | Advanced and Pro, both priced only as "Request quote" |
| Institutional extras | Institutional archive you can create and search, search in closed depositories and libraries, onboarding and a personal account manager, VIP support, "Uptime 99.99%" |
| Interface languages | Advanced lists English, German, French, Portuguese or Spanish. Pro lists "Any" |
| Individual pricing | "Check 2 pages for free", then "Everything you spend is $5.99 for 20 pages", described as "No monthly fees" |
| Support | support@plagiarismcheck.org and +1 844 319 5147, listed as 24/7 |
The site also states it is "Trusted by the 200+ Academic Institutions Worldwide", that it has "served over 77,000 users from 72 countries", and that "more than 9,300,000 works have been checked". Those are the vendor's own figures and we report them as such. Its student facing page also claims "99% accuracy in detecting even slightest signs of AI", again their claim, which we neither endorse nor compare against.
There is a published refund policy with a version history, the current version dated 10 December 2025, and named staff contacts in the footer. For an institutional purchase, both of those matter more than most feature bullets.
The individual. You are a student, freelancer or blogger. You want to know whether a document has uncited overlap with published sources before you submit or publish it. Two free pages, then $5.99 for twenty pages, with nothing renewing. Your alternative needs to be another similarity checker, not a detector.
The institution. You are buying for a department or a school. What you are really paying for is the archive of your own students' prior submissions, the ability to search closed depositories, grade passback and roster sync through your LMS, onboarding for staff who will not read documentation, and someone answerable when it breaks in week one of term. Price is quoted, not listed, because the deal is scoped per institution.
Those are not the same purchase and no single replacement covers both well.
This needs saying plainly, because it is the most common mistake in this category. Similarity checking and AI detection answer different questions.
Similarity checking asks: does this text overlap with a source that already exists? It is evidence based. It can point at the document it matched, with a percentage, and a human can open both and judge. Reports survive appeals because the evidence is inspectable.
AI detection asks: does this text pattern like machine generation? It is statistical. There is no source to point at, only a probability, and every tool in the category produces false positives. That includes ours.
If your institution's integrity process depends on showing a student what their work matched, you need a similarity engine and a corpus. Swapping in a detector removes the evidence and leaves you with a number.
You need an institutional archive. Storing and searching your own prior submissions is what catches recycled work between cohorts, and it only exists if your vendor builds it. Nothing in a detection tool substitutes for it.
You need LMS integration that already exists. Seven named integrations plus documented API access is a real asset. A migration that ends with teachers copying text into a browser tab will be abandoned by half term.
You want a quoted deal with support attached. Onboarding, training, a named account manager and a published uptime figure are the things procurement asks about. Self serve tools rarely offer any of them.
You want interface languages beyond English. The Advanced tier lists five interface languages and the Pro tier lists "Any". If your staff do not all work in English, this is not negotiable.
You are an individual buying occasionally. Two free pages and $5.99 for twenty pages, with no recurring charge, is hard to beat for someone who checks a few papers a year.
TextSight has no plagiarism checking. No corpus, no source matching, no institutional archive, no LMS integration, no grade passback. If any of that is why you are on PlagiarismCheck.org, this page is not proposing a replacement, and you should read the rest as an add on rather than a swap.
What TextSight does is a fast AI check with no account: 3 checks a day for anonymous visitors, pooled across the AI Detector and the Document Detector, capped at 1,000 words per check, with a 25 word minimum. A free account raises that to 60 checks a day at 5,000 words, and every signed in scan is saved to Scan History on all plans including free. Scores are shown as bands: under 30 likely human written, 30 to 69 mixed signals, 70 and above likely AI generated.
Paid plans are $9.99 a month for Starter, $19.99 for Pro, $39.99 for Business and $79.99 for Enterprise, each 25 percent lower billed annually at $7.49, $14.99, $29.99 and $59.99. Sentence level analysis and PDF export start at Starter. File upload, URL scan and bulk scan are part of the product. The Chrome extension and REST API start at Pro. Teams and branded reports start at Business. Starter allows 200 checks a day, Pro and above are unlimited.
The disclosure that matters most for schools: our detector is an English only ensemble of DeBERTa, RoBERTa and ELECTRA, and it carries a known false positive bias against writers who learned English as a second language. If you serve international students, that bias will land on exactly the students least able to contest it. Any institution weighing this should test it against its own cohort's writing before it goes anywhere near a misconduct process, and should not use it on non English submissions at all.
The deeper head-to-head: feature table, where GPTZero wins, where TextSight wins, and migration steps.
Read the comparePerplexity, burstiness, and transformer scoring explained, so you can read any detector's verdict critically.
Read the guideWhy detectors over-flag ESL and formal writing, and how sentence-level evidence helps you defend real work.
Read the guideThe full ranking with detection approach, pricing, and use-case fit side by side.
See the rankingStart with TextSight's free tier. No card, no signup, no commitment. Your first scan in about six seconds, with the evidence shown line by line.
Honest comparisons vs other tools.