Plagiarism Checkers Compared 2026: 12 Tools Tested

Updated on September 2, 2026

This comparison of plagiarism checkers for 2026 shows which of twelve premium tools actually detect verbatim borrowing, paraphrases and passages translated from English into German. Every provider was tested with the same document and the same 50 test cases. Mimir Mentor, an AI-supported platform for academic work, scores 80 out of 100 points and comes in ahead of Scribbr and Paperpal, which score 54.5 points each.

What counted was not some arbitrary similarity score. We assessed whether a known test case was found, flagged sensibly and backed up with a usable original source. That makes it easier to judge which plagiarism checker really helps students revise their work before they submit.

Transparency: This comparison was published by Mimir Mentor. Our own product is part of the test. That is why we disclose the methodology, the full ranking, the false positives and the weaknesses of the winner as well. The results are a documented snapshot from August 2026.

Writing in English? Four of the five categories — copy-paste, medium and strong paraphrases and the false-positive control cases — test detection mechanics that do not depend on the language of your paper, and the same goes for pricing, report quality and source display. Only the translation category is tied to the German test document. If you are checking an English thesis, read that one category as an indicator of how deeply a tool searches beyond literal word matches.

Which plagiarism checker wins in 2026?

Mimir Mentor wins our comparison with 80/100 points. The tool found all ten copy-paste cases in full, complete with the original source, reached 77.5 percent on medium paraphrases, 42.5 percent on strong paraphrases and 80 percent on translations. None of the ten control cases produced a false positive.

A quick note on how to read the table: the percentages show how much of the available score a tool picked up in that category. For price, € stands for under 10 euros, €€ for 10 to 20 euros and €€€ for more — a rough figure for a single check of a paper this length, since one-off purchases, credits and subscriptions are hard to compare exactly. Exact prices are listed in the tool profiles. Scribbr and Paperpal share second place, Copyleaks and PlagiarismCheck.org share seventh.

The key results at a glance:

• Mimir Mentor wins with 80 out of 100 points and was the only tool to find every copy-paste case in full, complete with the original source.
• Apart from Mimir (80 percent), no tool detects translations from English to any meaningful degree; the best competitor reaches 22.5 percent.
• No tested tool currently detects strong, substantially rebuilt paraphrases reliably; even the winner manages only 42.5 percent.
• 8 of 11 competitors wrongly flag the standard declaration of authorship as plagiarism.

The gap opens up mainly on passages whose content has been changed. Several competitors are strong on verbatim copies but lose ground sharply as soon as the sentence structure or the language changes. That makes a comparison by category more informative than a single percentage. Exactly how we tested and scored is set out in the test setup at the end of this article.

What do copy-paste, paraphrases and translations show in the test?

Plagiarism is the unattributed use of someone else’s intellectual work — and that is by no means always just copied text. If you take a passage word for word, restate it in your own words or translate it from English without naming the source, you are plagiarizing in all three cases. So not all plagiarism is alike: the forms differ mainly in how hard they are to detect.

That is exactly what the test reflects: verbatim borrowing (copy-paste), medium and strongly reworded paraphrases and English-to-German translations — plus control cases that must not trigger any alarm. Many scanners mainly check for word similarity and therefore miss precisely the reworded and translated variants. The linked guide gives you an overview of all types of plagiarism.

So a good plagiarism checker should not just search a lot of web pages. It has to show the finding in the right place and supply a source you can use to correct the text. Here is how the twelve tools performed in each category:

Copy-paste: Mimir finds 10 out of 10 original sources

Copy-paste is the compulsory discipline. Mimir Mentor was the only tool to score a full hit with the original source in all ten cases, giving it 30 out of 30 points. BachelorPrint reached 95 percent, Scribbr and Paperpal 90 percent each. Other providers missed even verbatim passages from a Springer journal article and a university repository entirely.

What to watch out for when you borrow text directly is covered in the article on copy-paste plagiarism.

Medium paraphrases: Paperpal and Scribbr stay strong

On medium paraphrases, Paperpal came out just ahead of Scribbr with 87.5 percent against 85 percent. Mimir Mentor reached 77.5 percent. Most of the remaining tools stayed at 35 percent or below. In this category Mimir missed one case from a university repository that Scribbr and PlagAware found.

For context: medium paraphrases stay close to the original — the sentence structure holds and only individual words are swapped. That is exactly the pattern that word-similarity systems such as the Turnitin technology behind Scribbr and Paperpal catch reliably. Mimir, by contrast, checks at the level of meaning. That explains its large lead on strong paraphrases and translations — and the small gap in the close range of word similarity, which is already being worked on.

Restating something in your own words is not automatically acceptable. A paraphrase needs a citation too if the underlying idea or information comes from a source. The guide to paraphrasing properly shows you how to do it cleanly.

Strong paraphrases: no tool detects them reliably

Strong paraphrases were the hardest category. Mimir Mentor led with 8.5 out of 20 points, or 42.5 percent, but missed four of the ten cases entirely. The best competitor, GoThesis, reached 3.5 out of 20 points. The conclusion is clear: heavily rebuilt passages whose content is still borrowed are currently not detected reliably by any tested tool.

Translation plagiarism: a blind spot for almost every provider

On English-to-German translations, Mimir Mentor reached 16 out of 20 points and found eight of ten cases in full, complete with the original source. GoThesis was the best competitor with 4.5 out of 20 points, but mostly delivered weak signals. Scribbr managed one partial hit; Paperpal and PlagiarismCheck.org produced no usable hit at all.

One example from the test makes the difference tangible: a passage from NASA’s climate pages is freely available online, and the test document contained its German translation. Only Mimir Mentor found it and backed it up with the original source. Word similarity stops at the language border; the borrowed content does not. The linked article explains in detail why translation plagiarism is so rarely caught.

False positives: four tools stay clean on every control case

Mimir Mentor, Copyleaks, PlagiarismCheck.org and GoThesis triggered no false positive on any of the ten control cases. Eight competitors treated the usual declaration of authorship as a problematic match. Five tools even flagged the freely written acknowledgements. GPTZero had the highest count with four false positives.

How do the five most important plagiarism checkers perform?

The profiles below focus on detection performance, false positives, report logic and pricing model. Convenience features were not scored separately. Despite its shared second place, Paperpal appears in the collected section further down: it uses the same Turnitin technology as Scribbr with an almost identical result profile and plays hardly any role in the German-speaking market.

Mimir Mentor: 80/100 points and first place

Result: Mimir Mentor achieves the highest overall score and the best results for copy-paste, strong paraphrases and translations. On medium paraphrases, Scribbr and Paperpal come out ahead of Mimir.

Report: Mimir classifies findings as copy-paste, paraphrase, translation plagiarism or unsupported claim. Every passage comes with an explanation, a suggested fix and a linked source. And the search is not limited to the web: Mimir also compares texts against academic sources from its own database. The report is deliberately designed as an interactive workspace: you can tick findings off, move sources you have found straight into your reference manager and research missing citations from within the report. The same premium scan also includes AI detection and academic text correction; our guide on combining AI detection and plagiarism detection in one step shows how these work together. A public sample report can be viewed without signing up.

Price and data protection: According to the Mimir product page, a single scan costs €13.95 up to 15,000 words, €23.95 up to 50,000 words or €33.95 up to 100,000 words. Subscriptions include several premium scans per billing period, which makes the individual scan cheaper. That covers the typical cycle of checking, revising and running a final check. Documents are not added to a plagiarism database and are deleted automatically after 30 days. The report stays available in your account.

• All ten copy-paste cases detected in full, complete with the original source
• Best result for strong paraphrases and translations
• No false positives across ten control cases
• AI detection and text correction included in the same scan
• No PDF export of the report at the time of testing (currently on the roadmap)

Verdict: The winner, with the broadest detection across all categories and no false positives. A good fit for German-language final theses where paraphrases, translations and missing citations need checking alongside verbatim copies.

Scribbr: 54.5/100 points and joint second place

Detection: Scribbr is strong on copy-paste at 90 percent and on medium paraphrases at 85 percent. Strong paraphrases reach 7.5 percent, translations 5 percent. The acknowledgements and the declaration of authorship produced two false positives.

Report and price: The premium report shows similarities, sources and a direct text comparison. Technically the check is based on an official partnership with Turnitin, whose database many universities also use. The official Scribbr price list quotes €17.95 up to 7,499 words, €28.95 up to 49,999 words and €39.95 for longer papers, in each case without a subscription.

• 90 percent on copy-paste, based on the Turnitin database
• 85 percent on medium paraphrases
• One-off purchase without a subscription, report as a download
• Practically blind to translations at 5 percent
• False positives on the acknowledgements and the declaration of authorship

Verdict: A strong choice for verbatim borrowing and moderately reworded passages. A good fit if you want an established one-off check on a Turnitin basis and do not need translation checking.

BachelorPrint: 43/100 points and fourth place

Detection: BachelorPrint reaches 95 percent on copy-paste, the second-best result in this category. Medium paraphrases come in at 27.5 percent. Strong paraphrases and translations were not detected. The declaration of authorship triggered one false positive.

Report and price: There is no web interface of its own; the report is sent exclusively as a PDF by email. For the test document of up to 8,000 words the public price was €16.90, with no registration required. BachelorPrint highlights automatic deletion after 24 hours as a data protection feature.

• 95 percent on copy-paste, the second-best result in the test
• One-off purchase without registration, deletion after 24 hours
• Strong paraphrases and translations completely undetected
• No interactive report, only a PDF by email

Verdict: Reliable on verbatim borrowing, with barely any detection beyond that. A good fit for a quick, anonymous verbatim check before you submit.

PlagAware: 41.5/100 points and fifth place

Detection: PlagAware achieves 85 percent on copy-paste and 30 percent on medium paraphrases. Strong paraphrases and translations each come in at 5 percent. The acknowledgements and the declaration of authorship produced two false positives.

Report and price: The German, TÜV-certified provider offers a detailed source view and a downloadable report. The prepaid package costs €12.90 for 100 page credits. Credits do not expire, and according to the provider, re-checking a revised version is free.

• A solid 85 percent on copy-paste
• Fair prepaid model, credits do not expire, free re-scans
• German provider, TÜV-certified, servers in Germany
• Barely any detection of strong paraphrases and translations
• False positives on the acknowledgements and the declaration of authorship

Verdict: A solid German provider with the fairest prepaid model in the test. A good fit if the server location and repeated checks of the same paper matter to you.

Copyleaks: 34/100 points and joint seventh place

Detection: Copyleaks reaches 70 percent on copy-paste but missed two verbatim borrowings from academic sources entirely. Medium and strong paraphrases as well as translations each came in at 5 percent. On the plus side, no control case triggered a false positive.

Report and model: Copyleaks distinguishes between identical passages, minor changes and paraphrases, and combines the report with AI detection. The category label alone, however, is no proof of strong paraphrase detection. In the test it picked up only 5 percent of the available paraphrase points. Payment is by credit packages rather than a subscription; 100 credits cost US$16.99 and cover several checks of this size.

• No false positives across ten control cases
• Credit packages instead of a subscription, AI detection in the same report
• Only 5 percent on paraphrases despite having its own paraphrased category
• Two verbatim borrowings from academic sources missed

Verdict: Clean control cases and a flexible credit model, but weak on anything that is not verbatim. A good fit for users working internationally with a focus on AI detection.

Which other plagiarism checkers were tested?

We also tested Paperpal, QuillBot, PlagiarismCheck.org, GPTZero, GoThesis, DupliChecker and Smodin. Paperpal reaches 54.5 points with Scribbr’s Turnitin technology; the remaining tools land between 24.5 and 36 points, each with individual strengths.

Paperpal: 54.5/100 points and joint second place

Paperpal shares second place with Scribbr and, by its own account, relies on the same Turnitin technology — the result profiles are almost identical: 90 percent on copy-paste, the best result on medium paraphrases at 87.5 percent, but no usable hit on translations and two false positives. The academic writing suite is aimed above all at an international research audience. The full plagiarism check is only available with a subscription (Prime, US$25 per month, 10,000 words per month); a free standard report of up to 7,000 words per month shows only a similarity range and the main sources. Only the premium scan was scored.

QuillBot: 36/100 points and sixth place

Like Scribbr, QuillBot belongs to the US group Learneo, but it clearly uses different technology for its plagiarism check. In the test it reached 56.7 percent on copy-paste and 27.5 percent on medium paraphrases, and mostly stayed at partial hits in the remaining categories. One control case triggered a false positive. At the time of testing, the plagiarism check was part of the premium subscription with a monthly word allowance. One other thing stood out in the test: after canceling the subscription, the finished report was no longer accessible. If you want to keep the report, save it before your subscription ends.

PlagiarismCheck.org: 34/100 points and joint seventh place

At 35 percent on medium paraphrases, PlagiarismCheck.org did better than several higher-ranked tools. On translations there was no hit at all. On the plus side were the direct side-by-side view of the passage and the source, and zero false positives.

GPTZero: 30.5/100 points and ninth place

GPTZero is known primarily as an AI detector. Its plagiarism check reached 66.7 percent on copy-paste but stayed weak on paraphrases and translations. Four of the ten control cases were wrongly flagged, the highest count in the test.

GoThesis: 30/100 points and tenth place

GoThesis had an unusual profile: only 25 percent on copy-paste, but the best competitor result on strong paraphrases at 17.5 percent and 22.5 percent on translations. There were no false positives. The report classifies findings as exact, as matching in meaning or as a missing citation.

DupliChecker: 25.5/100 points and eleventh place

On copy-paste, DupliChecker mostly found only parts of the passages and came in at 53.3 percent. Not one medium paraphrase was detected usefully. Two control cases triggered false positives. The offering is aimed more at budget-conscious short-term users and comes with various subscription terms.

Smodin: 24.5/100 points and twelfth place

Smodin reached 33.3 percent on copy-paste and 25 percent on medium paraphrases, and triggered three false positives. Because of its limit of 12,000 characters, the identical document had to be checked in three parts. This difference was documented transparently and was not penalized further in the scoring.

Which plagiarism checker suits which use case?

The short answer: in this test, Mimir Mentor is the first choice for almost every use case — it leads in three of the four detection categories, is one of four tools without a false positive and is available as a one-off purchase. The table shows which alternatives are also worth considering depending on your priorities. The guide to the plagiarism check for a bachelor’s thesis shows what a check before submission looks like in practice.

Turnitin itself is deliberately absent from the ranking. According to its official help center, the provider does not sell individual licenses to students or researchers. Access is normally through an institution. Turnitin technology is nevertheless represented twice in the test, because Scribbr and Paperpal both rely on it. Detailed Turnitin experiences with costs and alternatives are summarized in the linked article.

Providers’ prices differ by word count, subscription term and report scope. For a single final thesis, a one-off purchase or prepaid is often easier to budget for than a monthly or annual subscription. If you use a free check, you should also look at whether it shows only a risk value or already lists all findings and sources. Free versions were not scored in this comparison.

Whichever tool you use, one thing holds: software supplies indications, not a legally binding verdict. Check every finding, correct missing citations and compare longer flagged passages against the original source. The overview of plagiarism types helps you interpret them, and the article on how professors check for plagiarism takes a look from the examiner’s side.

What is the best plagiarism checker in 2026?

Mimir Mentor is the best plagiarism checker of 2026 in this test. The deciding factors are 80 out of 100 points, full hits on all ten copy-paste cases, 80 percent on translations and zero false positives. Scribbr and Paperpal follow with 54.5 points each and are particularly strong on medium paraphrases.

The result is not a promise of perfection. Mimir too failed to detect more than half the available points on strong paraphrases, missed one medium paraphrase and offered no PDF export at the time of testing. A plagiarism checker reduces the risk of overlooked sources, but it replaces neither careful citation nor your own subject-matter review.

Mimir Mentor keeps developing its detection. Current checks may therefore differ from the test state documented here — most likely for the better. For the final language check, our comparison of spelling and grammar checkers is a useful complement.

How was the plagiarism checker comparison carried out?

All twelve tools received the same content and were scored against the same grid. The test document ran to around 4,250 words across 18 standard pages. One editor operated every provider personally, reviewed every finding individually and transferred the result into the scoring matrix. No automated scoring took place. The article How does plagiarism detection work? explains how a plagiarism check operates technically.

Which 50 cases did the test document contain?

The 50 cases are spread evenly across five categories. We used German-language websites, open-access journal articles, university repositories, official sources and English original texts. That keeps the test aligned with the mix of sources in a typical academic paper in the German-speaking region.

The control cases included free academic prose, a table, a correctly attributed quotation from Kant, a personal acknowledgements section and a declaration of authorship. These formulaic components in particular show whether a tool separates harmless matches from passages that actually need work.

The paraphrases were calibrated quantitatively rather than written by feel. Medium paraphrases retain 55 to 80 percent of the original words, strong ones 40 to 55 percent with rebuilt sentences. Every text was measured against its target band before it entered the data set. That is a deliberate difference from many well-known comparison tests, whose paraphrase cases are often only minimally altered, with just individual words swapped. Realistic, substantive rewording, by contrast, exposes precisely the weakness of checkers that primarily match on word similarity.

Part of the translation cases is based on Scribbr’s official test document, which we requested directly from the provider for this comparison. Because it is in English, these passages were tested as English-to-German translation plagiarism. The test therefore deliberately competes on the market leader’s own ground, partly with its own test data, and Scribbr’s own comparison candidates such as PlagAware, Copyleaks, DupliChecker and Smodin are included as well.

How were findings scored?

Each detection case was worth 0 to 2 points. A tool only received two points if it flagged the passage and named the exact original source or the original article. Partial flags, substitute sources and unusable hits received correspondingly fewer points.

Copy-paste could reach a maximum of 30 points. That included a bonus point for every full hit with the original source. Medium paraphrases, strong paraphrases and translations were each worth a maximum of 20 points. Ten clean control cases were worth another 10 points. False positives only reduced the relevant control point and were not deducted twice.

How fair and reproducible was the test?

• In every case we used the premium scan with the maximum available settings.
• The same document was uploaded as a DOCX or as a PDF with identical content.
• The document contained no URLs, source titles or DOIs as hints.
• Because of its limit of 12,000 characters, Smodin had to be split into three parts with identical content.

The test design and the anonymized test data set are available from the Mimir team on request, along with the detailed results table if you want it. All providers keep developing their systems. A live test may therefore differ from the results documented here; the comparison reflects the state of play in August 2026.

FAQ about the plagiarism checker comparison