Best Plagiarism Checkers Compared

The best plagiarism checker should detect plagiarism the most accurately, even when the original phrasing has been altered. It should also provide a clear, comprehensive plagiarism report.

To identify the best plagiarism checker, we compared the performance of 12 checkers through an in-depth research process. We uploaded plagiarized texts that were either directly copied and pasted from multiple sources or edited to varying degrees. In total, we used 140 sources to construct our test documents.

Overview of total scores per plagiarism checker, based on the amount of detected plagiarism:

Our process for comparing checkers

In order to find the best plagiarism checker, we analyzed different aspects of the tools, focusing on both depth and breadth.

We based our analysis on the following factors:

• Access to the biggest and most varied database
• Ability to detect the most plagiarism for the most source types
• Ability to detect plagiarism when the plagiarized texts have been paraphrased
• Highest quality of matches
• Level of user-friendliness and trustworthiness

We used the same test documents, evaluation criteria, and data analysis for each tool in order to objectively compare the plagiarism results side by side. This ensured that the results required very little interpretation on our part.

Also see our list of the best free plagiarism checkers and the best AI detectors.

1. Scribbr review 

“Catches plagiarism more accurately than any other checker”

Quality of matches

Scribbr performed well for all source types relevant to students, such as journal articles and dissertations.

Most importantly, Scribbr’s checker was the most successful at detecting plagiarism in source texts that had been heavily edited to mimic accidental paraphrasing plagiarism.

Scribbr was also able to find full matches. This means the entire plagiarized portion is matched correctly to just one source.

Usability

The results are presented in a clear, downloadable overview. Different colors are used for different sources, making it easy for users to assess each plagiarism issue separately.

Issues can be fixed with Scribbr’s free Citation Generator, which generates proper citations for any missed or improperly cited sources.

Users can also choose to combine the Plagiarism Checker with the Self-Plagiarism Checker, which is unique to Scribbr. This tool allows users to upload their own unpublished documents in addition to the public database.

Instead of requiring users to subscribe to their services, Scribbr charges per plagiarism check ($19.95–$39.95, depending on the word count).

However, users are unable to work directly in the tool, and it is not possible to recheck your document for free.

Trustworthiness

Scribbr does not store the uploaded documents, sell them to third parties, or share them with academic institutions. Data is automatically deleted after 30 days, or students can opt to manually delete their document after the check.

Scribbr has live and responsive customer support to assist users in multiple languages. There is easy access to a plagiarism checker guide and other free resources about plagiarism.

Scribbr also has a happiness guarantee, where users receive a new check or refund if they aren’t satisfied for any reason.

Try Scribbr’s Plagiarism Checker now

2. PlagAware review 

Quality of matches

PlagAware was often able to find full matches and attribute the text to the correct source. However, it performed poorly with heavily edited texts.

For sources that had been edited, the tool often highlighted the entire paragraph as plagiarized, not distinguishing the parts that had been paraphrased from those that had not.

Usability

The website report is easy to navigate as it uses different colors for sources. The tool has a function that tells you how many words a plagiarized section has and gives a similarity percentage.

Unfortunately, the downloadable report is confusing to read as it uses only one color for all sources.

Users pay per page of scanned text. A packet of 100 pages is €12.99 (USD prices not listed on the website).

Trustworthiness

According to their website, users can delete documents from their profile at any time. 

There is no live support, but there is a contact form and phone number that can be used to contact support.

Discover Plagaware’s plagiarism checker

3. Compilatio review 

Quality of matches

Compilatio was able to find quite a few of the plagiarized sources, but it struggled if the source text had been heavily edited.

When it was able to identify a source, it was often correct, but the tool’s performance seemed to decline toward the middle and end of documents.

Usability

Compilatio’s downloadable report is very easy to read and clearly links to each plagiarized source. However, it is not clear which part of each paragraph is being marked as plagiarism, as the text is not highlighted.

The tool scans the text against other documents you have uploaded, which can help to avoid self-plagiarism.

Users can buy packages of credits starting at €4.99 (for 5,000 words). These credits can be used for multiple documents and are valid for 12 months after purchase. Monthly plans are also available.

Trustworthiness

Compilatio does not share or sell submitted documents, and the documents are not used as comparison material for other users.

There is no live support available, but they do provide a helpdesk with FAQs and a request form.

Discover Compilatio’s plagiarism checker

4. Prepostseo review 

Quality of matches

Prepostseo’s tool is sometimes able to find full matches and generally attributes plagiarized text to the correct source. However, with edited texts, it sometimes marks only part of a paragraph as plagiarized.

It missed many instances of plagiarism at all levels of editing, especially those that came from scholarly sources.

Usability

The online report does not use different colors to differentiate between different sources. It does link to the plagiarized source, though. However, the PDF report does not indicate in any way which text is from which source.

The tools offered by Prepostseo to eliminate plagiarism are nice, but they did not always function smoothly.

A basic subscription plan costs $10/month and includes plagiarism detection for 5,000 sentences.

Trustworthiness

There is a contact form on the website but no live support. Prepostseo does not store or share uploaded content.

Discover Prepostseo’s plagiarism checker

5. Grammarly review 

Quality of matches

Grammarly found a relatively low amount of plagiarism. It scored lower than 40% in all rounds of testing.

When it did find plagiarism, the tool was often able to find the right source. However, the matches were usually only partial and rarely included the entire plagiarized section.

Usability

The design is not very clear. As the tool is primarily used as a language checker, the plagiarism checker function is somewhat difficult to find. The tool uses the same color for all sources, making it hard to read. Additionally, you have to split longer texts into two parts in order for the scan to run.

The subscription comes with a language and style tool and offers a citation assistant that helps generate the missing citations. There is a 100,000 character limit per document uploaded. Additionally, there is a 150,000 total word limit per month for both the monthly ($30 per month) and the yearly plan ($12 per month).

For more information, you can read our in-depth Grammarly review.

Trustworthiness

Grammarly does not store, sell, or share documents with other parties.

There is a support page with tips, tutorials, and FAQs, and it is possible to submit a question via a form. However, there is no live support.

Discover Grammarly’s plagiarism checker

6. DupliChecker review 

Quality of matches

While DupliChecker was able to identify more than 40% of the plagiarized material, it was not able to identify full matches. That is, when entire sentences were plagiarized, it only identified part of the sentence as plagiarized material.

Usability

The tool is easy to use, with a clean interface. However, the scan took longer than average to run. In the downloadable report, plagiarized text is not connected to its source, which makes it difficult to identify exactly what text is plagiarized. DupliChecker does keep a history of users’ scans.

Subscription plans start at $5/week (for 10,000 words).

Trustworthiness

According to DupliChecker’s website, user documents are not saved. There is a contact form on the website but no live support.

Discover DupliChecker’s plagiarism checker

7. Check-Plagiarism review 

Quality of matches

Check-Plagiarism found less than 40% of the plagiarized text in edited documents. The tool performed particularly poorly for scholarly sources. It was able to find some full matches but often returned only a partial match.

Usability

The report is difficult to read because red is used for every source and the formatting of the original is not preserved. In the PDF report, the sources are not linked directly from the text, which diminishes its usefulness. The document had to be divided into two to be scanned because of character limits. On the plus side, there is a history of scans performed.

Subscription plans start at $6.99/week (for 10,000 words).

Trustworthiness

According to the Check-Plagiarism website, documents are not saved or shared with third parties. There is a contact form but no live support.

Discover Check-Plagiarism’s plagiarism checker

8. Copyleaks review 

Quality of matches

Copyleaks performed relatively poorly with all source types. However, it was sometimes able to attribute an entire source block to the correct source.

The report distinguishes between text that is “identical” to a source, text that contains “minor changes,” and text that is “paraphrased.” However, its judgment is sometimes wrong.

Usability

The site report allows users to click part of the text and pull up the plagiarized source, but this is not possible in the downloadable report, which only lists all sources at the top. Additionally, in the report, 100 sources had been disabled. We had to enable them manually in order to have the report reflect a true plagiarism percentage.

The reports are difficult to read, as they use the same color highlights for all sources. Additionally, results are given sentence by sentence. To tell if an entire paragraph is plagiarized from the same source, you must click on each individual sentence.

Annual subscriptions start at $8.99/month (for 300,000 words).

Trustworthiness

Copyleaks claims that they “will never steal your work.” To permanently remove uploaded content from their database, though, users must contact customer support. The website has a chat option and a contact form.

Discover Copyleaks’s plagiarism checker

9. Small SEO Tools review 

Quality of matches

Small SEO Tools identified very few full matches, often marking sentences in the middle of an entirely plagiarized text as original material.

Additionally, when a scan was run a second time, the percentage of plagiarized material changed, indicating low reliability.

Usability

The PDF report is very difficult to read because all of the sources are marked in one color, and there are no clear links from the text to its source. The formatting of the original document is not preserved in the report.

Small SEO Tools plans start at $9.80/month for 40,000 words.

Trustworthiness

Small SEO Tools states that user files are immediately deleted once the scan has been run. They have a contact form on their website but do not offer other forms of support.

Discover Small SEO Tools’s plagiarism checker

10. Plagiarism Detector review 

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Quality of matches 

Plagiarism Detector was unable to find full matches, attributing individual sentences, rather than the entire section, to one or more sources. Overall, it found less than 40% of plagiarized content, and it performed particularly poorly with scholarly sources.

Usability 

In the downloadable report, the format of the text is lost, making it hard to read. The list of sources is also difficult to cross-reference with the text above because the same colors are used for different sources.

Plagiarism Detector offers a rewrite tool to help resolve similarities, but the quality of this tool is questionable, and it does not help with the citation issues. You should resolve plagiarism by citing the relevant source, not by attempting to rewrite the text to disguise it.

Subscription plans start from $5/week (for 15,000 words).

Trustworthiness

Plagiarism Detector does not store or sell uploaded documents. There is no live support, but the website does offer a help request form.

Discover Plagiarism Detector’s plagiarism checker

11. Quetext review 

Quality of matches 

Quetext detected about half the plagiarized text but was often unable to fully match the entire source text to one source. Instead, individual sentences were attributed to different sources.

The tool also sometimes attributed plagiarized material to an incorrect source.

Usability 

Our testers found both the online report and the downloadable PDF almost impossible to work with. Both completely change the formatting of the text, making it difficult to tell what part of the paper plagiarized text comes from.

Additionally, sources are marked only in two colors (red for full plagiarism and orange for partial plagiarism), which makes it difficult to identify sources.

Plans start at $8.80/month.

Trustworthiness

Quetext does not store or re-upload your text, and it offers a help center with FAQs. There is no live support, but users can submit a help request on the website.

Discover Quetext’s plagiarism checker

12. Smodin review 

Quality of matches 

Smodin performed poorly in all rounds of testing. It was not able to find full matches, and in the heavily edited text, it found less than 10% of the plagiarized content. It often did not return even partial matches.

Usability 

The tool has a very low limit of 12,000 characters (not words) per scan.

Both the online report and the downloadable PDF report are difficult to read. The downloadable report displays the uploaded document, but it doesn’t highlight the text that it flags as plagiarized. Instead, below this, it includes the individual parts of the text that it recognizes as plagiarism.

Plans start at $12/month.

Trustworthiness

According to their website, documents are not saved or shared with third parties. There is no live support, but there is a help page and contact form on the site.

Discover Smodin’s plagiarism checker

Go back to the best plagiarism checker

Frequently asked questions about plagiarism checkers

How is plagiarism detected?

Plagiarism can be detected by your professor or readers if the tone, formatting, or style of your text is different in different parts of your paper, or if they’re familiar with the plagiarized source.

Many universities also use plagiarism detection software like Turnitin’s, which compares your text to a large database of other sources, flagging any similarities that come up.

It can be easier than you think to commit plagiarism by accident. Consider using a plagiarism checker prior to submitting your paper to ensure you haven’t missed any citations.

Are plagiarism checkers accurate?

The accuracy depends on the plagiarism checker you use. Per our in-depth research, Scribbr is the most accurate plagiarism checker. Many free plagiarism checkers fail to detect all plagiarism or falsely flag text as plagiarism.

Plagiarism checkers work by using advanced database software to scan for matches between your text and existing texts. Their accuracy is determined by two factors: the algorithm (which recognizes the plagiarism) and the size of the database (with which your document is compared).

Can you use Turnitin for free?

Yes, Scribbr offers a limited free version of its plagiarism checker in partnership with Turnitin. It uses Turnitin’s industry-leading plagiarism detection technology and has access to most content databases.

Run a free plagiarism check

If you’re a university representative, you can contact the sales department of Turnitin.

To which databases will my document be compared?

Your document will be compared to the world’s largest and fastest-growing content database, containing over:

• 99.3 billion current and historical webpages.
• 8 million publications from more than 1,700 publishers such as Springer, IEEE, Elsevier, Wiley-Blackwell, and Taylor & Francis.

Note: Scribbr does not have access to Turnitin’s global database with student papers. Only your university can add and compare submissions to this database.