You can use free online plagiarism checkers to avoid accidental plagiarism. But are these tools reliable and truly free? We put 12 popular free plagiarism checkers to the test.

We supplied test documents with 180 distinct source materials, either duplicated verbatim or altered to hide the plagiarism.

ConclusionOur research demonstrates that free plagiarism checkers cannot detect most plagiarism in our test documents, altered or unprocessed. In 2022, the Scribbr Plagiarism Checker is still the best alternative.

 

The table below compares our ranking of the free plagiarism checkers to the Scribbr Plagiarism Checker.

 

We tried to test Plagly, but it was unable to generate any reports, thus we couldn’t include it in our comparison.

 

To evaluate free plagiarism checkers, we asked four questions:

 

 

 

 

 

We used the same test documents, broken up to fit the tools’ word restrictions. The materials included text copied straight from sources and text altered in various ways.

 

We looked at the plagiarism percentages and if the tool found full matches (indicating the proper source for a full plagiarized text) or partial matches (matching different sentences to different sources).

 

Note: Our testing approach is described in this article.

 

Free vs. paid checkers

 

We discovered that free plagiarism checks often advertised falsely and were inferior to commercial programs in numerous ways. Our findings were as follows:

 

Review of Scribbr

 

 

 

Pros

 

 

 

Never stores or sells your data

 

 

The Self-Plagiarism Checker checks for plagiarism.

 

Cons

 

 

Free?

 

A subscription to Scribbr’s Plagiarism Checker is not required. Instead, you pay a flat rate ($19.95–39.95 depending on word quantity) for each plagiarism check. Unlike other services, there is no word limit.

 

Matches’ grade

 

Scribbr’s plagiarism checker, created in collaboration with Turnitin, beat all other free (and commercial) checkers, detecting 95% of plagiarism compared to an average of 21% for free checkers.

 

It fared well with student-friendly sources like journal articles and dissertations. It even found plagiarism in substantially altered materials, indicating it has no problem with paraphrasing plagiarism.

 

A full match would match the entire plagiarized material to the correct source.

 

Usability

 

Your results are in a simple downloadable report. Sources are color-coded to make it easier to read.

 

The errors mentioned can be remedied with Scribbr’s (free) Citation Generator, which generates properly structured citations wherever needed.

 

Scribbr also has a plagiarism checker. In addition to the public database, users can upload unpublished documents to check for self-plagiarism.

 

But you can’t alter text directly in the tool and you can’t re-check your document for free either.

 

Trustworthiness

 

We do not store, sell or share your documents. After 30 days, data is automatically removed, or students can individually delete their document.

 

Live customer help is available in different languages. Access to the Plagiarism Checker and other free tools on plagiarism is simple.

 

Scribbr also offers a money-back guarantee if you’re not happy with the tool.

 

Plagiarism Checker on Scribbr

 

  1. Quetext test

 

 

 

Pros

 

 

 

 

 

Cons

 

FALSE POSITIVES AND PART

 

 

 

 

 

Free?

 

Quetext offers a free trial of five “pages” (500 words). However, after scanning one 800-word document, the site said our free trial had ended and no more documents would be accepted.

 

Uploading files to Quetext is also a Pro feature. Not paying means copying and pasting text from your document.

 

For $9.99 per month (more expensive options are available), you can check up to 100,000 words.

 

Matches’ grade

 

Quetext finds more plagiarism (57%) than any other free checker, although it can’t match every source text to a single source. Assigning sentences to multiple sources leads to many false positives.

 

Quetext claims to verify against webpages and academic sources, however we found it lacking in detecting academic plagiarism.

 

Usability

 

Quetext’s scanning speed is slow. The plagiarism report is easy to read and understand. Similitudes in the text are highlighted.

 

Sources are not color-coded. Instead, partial matches are orange, while full matches are red. Clicking on a highlighted sentence displays the source text, along with a percentage of similarity.

 

Assisting in the correction of plagiarism by supplying citations. Sadly, it lacks durability. The citations created this method may be inaccurate, and you must manually provide data.

 

Trustworthiness

 

Quetext says it doesn’t save your text to a database and that it’s entirely encrypted.

 

The website has FAQs regarding the service and you may contact them via phone or email.

 

Quetext’s plagiarism detector

 

  1. Grammar check

 

 

 

Pros

 

 

 

 

Cons

 

 

 

 

Free?

 

Grammarly’s plagiarism detector isn’t free, as stated. The free service only tells you that you have plagiarism in your content without telling you where it is, how much it is, or where the sources are.

 

Then you’ll be directed to download the Grammarly app and pay $30/month for premium subscription. Even after purchasing, there’s a 100,000 character (20,000 word) limit.

 

Matches’ grade

 

Grammarly found full matches better than most free plagiarism checkers, and it frequently found the proper source. However, its overall percentage (43%) lagged below Quetext and Scribbr.

 

It did well with raw texts but not so well with edited ones. It frequently gave false positives.

 

Usability

 

Grammarly is a paid service with a more user-friendly interface than most free checkers. That same color is used for all sources, making results difficult to analyze.

 

The checker disables the original formatting when changing text, but restores it after downloading.

 

A language and style tool is included, as is a citation helper.

 

Trustworthiness

 

Notify me of updates to Grammarly.

 

The site has a help page with tips, tutorials, and FAQs, and a form for submitting questions. No live chat help.

 

Grammarly’s plagiarism detector

 

  1. Unicheck test

 

 

 

Pros

 

 

Non-sale and non-sharing of documents

 

 

Cons

 

 

 

 

Many matches in one sentence

 

Free?

 

Unicheck offers a free trial of 200 words. Even if your document is too long for this trial, you can still test the service before buying.

 

After the trial, the price is per page: $5 for 20, $10 for 50, and $15 for 100.

 

Matches’ grade

 

Most free plagiarism checkers couldn’t adequately match some copied passages to their source texts. However, the total percentages (44%) were similar to Check Plagiarism.

 

As a result, the report’s findings are not conclusive.

 

Usability

 

The report highlights plagiarism, but it’s all the same color, making it impossible to trace a sentence to a source quickly.

 

The reports are also difficult to comprehend because they cite many sources for a single statement, making it difficult to determine how to correct plagiarism.

 

Trustworthiness

 

Unicheck states that uploaded papers will not be sold or redistributed.

 

Live chat assistance and a lesson and guide center are provided.

 

Unicheck’s plagiarism detector

 

  1. Review Plagiarism

 

 

 

Pros

 

 

 

 

 

Cons

 

 

The report loses all text formatting.

 

Not a whole match, but a sentence match

 

 

Free?

 

Check Plagiarism appears to be free for most users, while the limitations remain unclear.

 

The site specifies the free upload limit as a number of “queries” (sentences) each month. In actuality, we were able to upload all our docs (about 30,000 words) without surpassing this restriction.

 

Matches’ grade

 

It discovered less plagiarism in unprocessed materials, but it did better with substantially altered texts. Its average score (44%) was not impressive.

 

Check Plagiarism failed to accurately identify any sources. Instead, it detected several partial matches, often displaying multiple sources for a single text.

 

As a result, numerous typical short sentences or even single words are labeled as plagiarized, indicating the checker’s methodology is highly untrustworthy.

 

Usability

 

Examine Plagiarism can check up to 5,000 words at once, making it more practical than other free solutions for longer texts. But the site is flaky, and the reports it creates are useless.

 

The report downloads as a single block with no formatting, then as individual text pieces colored red or green depending on whether plagiarism was found. In this section, the same text is repeated if many sources exist for it.

 

This is followed by a numbered list of the sources used to identify each case of plagiarism, which is impossible to cross-reference.

 

The site’s version of the report is slightly better. A “Compare” button next to the plagiarized content shows the source material. But it’s still a mess.

 

Trustworthiness

 

There is no internal database for Check Plagiarism’s reports, they claim.

 

The site has several FAQs, but the responses are vague and conflicting. For example, the word limit for an upload is stated as 10,000–15,000 words, while it is actually 5,000 words.

 

Check for Plagiarism

 

  1. Check for plagiarism

 

 

 

Pros

 

 

 

Cons

 

 

 

 

 

Free?

 

The Plagiarism Detector is free to use, but only up to 1,000 words. Paid upgrades bring the per-document word count up.

 

Each premium plan pays for a specified number of words rather than time, such as $10 for 30,000 words.

 

Matches’ grade

 

In general, Plagiarism Detector performed well for a free checker (32% ), but we ran into a serious technical issue that invalidated certain results.

 

It stops flagging plagiarism and displaying sources midway through longer documents. The plagiarism % presented appears to be based on a comprehensive scan of the text, however at a certain point, the report is meaningless.

 

Usability

 

Incomprehensible Plagiarism Detector reports The source is not shown while hovering over a copied part. Instead, it’s in a distinct list.

 

Trustworthiness

 

Plag Detector claims not to store or sell your documents. There is no live assistance, rather a help request form.

 

On the site, a rewriting tool claims to automatically rewrite material to avoid plagiarism. These services are immoral and unreliable.

 

Plagiarism Detector

 

  1. Post-SEO audit

 

 

 

Pros

 

 

(Highlighting)

 

 

Cons

 

 

 

Pages with lots of ads

 

 

Free?

 

Plagiarism checker by Pre Post SEO is free. You can only scan up to 1,000 words per search. This limit is abolished if you subscribe to their premium plan ($10-$45/month).

 

Matches’ grade

 

Like other free checkers, Pre Post SEO found partial matches more often than full matches. Even with unedited sentences, this checker struggled. The overall average was 29%.

 

Usability

 

The page hosting the checker is cluttered with unrelated adverts, making it difficult to use. Even if you pay for the premium plan.

 

Paraphrasing plagiarism is highlighted in a different hue than verbatim plagiarism in the report. In practice, the checker cannot dependably distinguish between the two.

 

Trustworthiness

 

No documents are stored or sold by Pre Post SEO. The site doesn’t have live assistance, however it does have a form.

 

Pre Post SEO, like some other sites, features a plagiarism checker. This tool isn’t reliable or ethical, and you’re better off dealing with difficulties manually.

 

Pre Post SEO’s plagiarism detector

 

  1. Review of Search Engines

 

 

 

Pros

 

 

 

 

Cons

 

 

 

 

 

 

Free?

 

It can scan up to 1,500 words at a time. With unlimited document uploads, this is a truly free service.

 

Matches’ grade

 

This plagiarism checker’s approach of finding matches appears unreliable. Every sentence in your paper is searched on Google, and if it matches, it counts as plagiarism.

 

It also shows 100% plagiarism without underlining all language in the document, indicating a lack of precision in the data provided.

 

It found only 23% of the plagiarism in our test documents, and its technique prevented it from finding any full matches.

 

Usability

 

On most sites, the scanning procedure takes several minutes per document. One paper took roughly a half an hour to scan for some reason.

 

The site’s assessment lists individual sentences marked as original or plagiarized. Each source has a link that just googles the sentence. However, it does not explicitly link each sentence to a source in the downloadable report.

 

Uploading a document with the “less than” symbol () created a problem that omitted any content after the symbol, rendering the results worthless.

 

Trustworthiness

 

Search Engine Reports says they don’t store any uploaded content. No registration is necessary to use the site.

 

The site has a “Article Rewriter” function that automatically rewrites material. We do not recommend this tool. Using a service like this to paraphrase content is illegal.

 

The Plagiarism Checker at SE Reports

 

  1. Review of SEO Tools

 

 

 

Pros

 

 

 

 

Cons

 

 

 

 

 

It scans phrases rather than whole texts

 

Free?

 

With Small SEO Tools, you may check 1,000 words for free.

 

You can scan more than one document each check, but you must complete Captchas to upload more than one. We were able to scan everything for free.

 

Matches’ grade

 

Only 22% of our test documents had plagiarism detected by Small SEO Tools. Because it analyzes each sentence sequentially, it could only find partial matches. It did well with unprocessed texts but not with altered texts.

 

The reports generated did not properly link plagiarized material with sources, making the results difficult to verify.

 

Usability

 

The Small SEO Tools plagiarism checker page is packed with adverts that easily confuse the buttons to push. The scanning is slow. The page takes a while to load, so you could think the upload failed.

 

Uploading a document using the “less than” symbol () produced an issue where the report omitted all content after the symbol, invalidating it.

 

The report itself is confusing. Even when the “Matched sources” option is chosen, all copied content is highlighted in one color and not clearly matched to its source.

 

Trustworthiness

 

Small SEO Tools claims not to save your material. This tool requires no registration. If you do register, you can contact support to deregister and delete your data.

 

The site also has a “Article Rewriter” that automatically rewrites material. We do not encourage employing tools that are inefficient and dishonest. Paraphrasing is used to demonstrate understanding of information.

 

See our plagiarism checker.

 

  1. DualChecker test

 

 

 

Pros

 

 

 

 

Cons

 

 

 

 

 

Free?

 

However, you can only upload 1,000 words at a time. With their premium plans, you can get up to 10,000.

 

If you wish to upgrade, the site has a dizzying array of premium options to choose from. Cost is $10/month.

 

Matches’ grade

 

DupliChecker discovered minimal levels of plagiarism (20 percent ). Because it scans sentence by sentence, it found some full matches.

 

Despite claiming to detect paraphrasing plagiarism, it performed poorly with edited texts. With unedited text, it was comparable to Small SEO Tools.

 

Usability

 

Sadly, DupliChecker’s website is full of adverts for other services and sites. In the report, an animated “Make it unique” button promotes their rewriting tool.

 

The report’s formatting is generally intact, making it readable. Plagiarized content is highlighted (albeit in one color) and can be clicked to reveal the source.

 

Trustworthiness

 

To prevent data leaking, the site claims not to save uploaded papers and deletes them after the inspection. There is no live assistance, however there is a contact form and a feedback form.

 

This site, like others, offers a “Paraphrasing Tool.” These tools are ineffective at producing cohesive content, and they violate academic writing norms.

 

DupliChecker

 

  1. Check for plagiarism

 

 

 

Pros

 

 

Cons

 

 

 

 

 

 

 

 

Free?

 

It promises to be free, but you can only upload five documents before you have to sign up for one of their several premium plans. The word limit for these publications is 800.

 

Premium plans allow increasing (but not removing) this word restriction. Paying $10 per month just boosts the limit to 1,000 words.

 

Matches’ grade

 

Plagiarism Checker had the poorest results of all the checkers we tested, at 16%. It could only return partial matches for a source text.

 

It found less plagiarism in unprocessed writings than most other technologies, and more in altered ones. Its plagiarism detection method appears unreliable.

 

Usability

 

The huge quantity of adverts on the Plagiarism Checker website makes it difficult to utilize. This includes pop-ups that appear during scanning and interrupt the process until clicked.

 

The scanning procedure can get stuck and not provide a report, forcing you to restart. The option to download your report doesn’t work, thus you can only view it while the page is open.

 

The report’s “Compare results” option simply googles the term in question, which is unreliable. No clear source overview.

 

Trustworthiness

 

No content is stored in a database or shared with others, the site states. “Our powerful AI-powered system assures that your work must be protected under the copyright laws,” it says.

 

They also have a “Paraphrasing Tool,” which is ineffectual and unethical.

 

Plagiarism Checker

 

  1. Reviewed by

 

 

 

Pros

 

 

 

Cons

 

 

 

 

 

 

Free?

 

Writer’s plagiarism checker comes in two flavors: web-based and browser-based. The website version is free and checks up to 2,000 words.

 

The browser extension requires a $11 monthly premium subscription, with a one-month free trial. We don’t encourage signing up because the checker doesn’t seem to work.

 

Matches’ grade

 

In our tests, Writer detected no plagiarism in any of our texts, indicating that this version is simply faulty.

 

No overall plagiarism % was displayed anywhere on the online version, therefore we couldn’t use our standard testing approach. While you can find matches to websites with matching text, they appear to be erroneous.

 

Usability

 

Although the Writer website is attractive, the checker itself is not user-friendly. Both versions only allow you to type or copy-paste text into the checker, not upload documents.

 

Unlike other checks, the internet version does not show an aggregate plagiarism percentage, simply individual matches. Awkward interface for scrolling through individual matches.

 

The checker also takes a long time to scan your text and gives no indication of its progress.

 

Trustworthiness

 

Writer claims its plagiarism checker is secure and won’t disclose your data with anyone. A thorough security policy is on another page.

 

Contact the company via numerous email addresses, including one for security concerns. There’s no live assistance, and the “Help Center” website is sparse.

 

Writer’s plagiarism detector

 

FAQs regarding plagiarism checkers

 

Is Turnitin free?

 

What is plagiarism?

 

Do plagiarism checkers work?

 

Whose databases will my file be compared to?