How Do Plagiarism Checkers Work?

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10 Nov 2022

Learn How Do Plagiarism Checkers Work

This guide explores the importance of plagiarism checkers, things they help to avoid, and the ways how to avoid plagiarism.

How Do Plagiarism Detectors Work?

Even though there are various plagiarism detectors that you may encounter free of charge and commercially, they use mostly the same algorithms that help them to compare your content to existing texts and publications. Learning how do plagiarism checkers work, you must remember that a lot will depend on the capacity of content databases that help to find similarities. While commercial plagiarism detection software won’t share their internal mechanisms, they still crawl the web and scan through the libraries like Jstor, Google Scholar, and PubMed to check for plagiarism. Once they find something that looks similar, it transfers to the final report and you get the link that helps to identify and determine the seriousness of the issue. It also makes it easier to correct things and avoid so-called false alarms when a part of a text has been triggered by wrong detection algorithms.

Some tools like TurnItIn take a slightly different approach by storing every piece of the scanned content in their database, thus creating an enormous list of assignments that have been submitted before. It has certain negatives as you cannot check your paper twice with this commercial tool without resulting in self-plagiarism as the document has already made it into their database. It brings up certain privacy concerns. The FixGerald plagiarism checker keeps this issue in mind and keeps your information safe by scanning through the various databases without storing your data.

The Differences In Plagiarism Checkers

Before you find out how do plagiarism checkers work, you must learn more about the major differences that can lead to specific results. It will also play a crucial role regarding how much they can scan and the things that one can detect. Here are the main factors of plagiarism detection to consider:

Scanner’s Database Size.

It is one of the most important issues with all plagiarism checkers since one can either scan website content or have an additional look through the online journals and the libraries. This leads us to the question of what is a plagiarism checker and how should it help. For example, when a medical paper is checked, an ability to access online databases like Pubmed will play a crucial role in the results. Otherwise, people would use Google for exact matching!

Scanning Quality.

Things will always remain different, depending on your essay type or the style of writing. If there are exact sentences that have been plagiarized in full, you will be able to detect them with most free scanners. The catch is that commercial tools will use “fingerprint” features for hidden plagiarism, yet it often results in false alerts and long conversations with the college staff.

Detection of Altered Content.

A far more important challenge is the detection of text that has been paraphrased or altered. Smart plagiarism detection tools that know how is plagiarism detected in mosaic cases will determine the severity of the likelihood and reflect it in a report.

Text Fragments VS Exact Matches.

Don’t forget that far not every commercial tool will implement the best technology and the detection methods just like not every solution that is offered free of charge is weak or insufficient. Learning how does plagiarism software work, you will see that fragments of text will be highlighted. Some will have odd words like “this has resulted in better…” that won’t make much sense plagiarism-wise. It is exactly where exact matching of the free tools works better.

Things Plagiarism Checkers Won't Catch

Let us not forget that plagiarism detection is based on artificial intelligence and a comparison of the keywords and phrases that have been encountered. Even with commercial tools, they cannot guarantee complete accuracy in their ways to detect plagiarism or provide a verdict. When you can use tools like FixGerald, there’s no reason to ignore an opportunity. Make sure to check things manually regarding the accuracy of your formatting and the quotes.

Most plagiarism scanners may not identify things that:

  • have been rewritten or paraphrased from another language with specific grammar.
  • multimedia elements and certain images where text recognition is unavailable.
  • appear in the university's private databases unless the tool has been modified. In such a case, adjusting how is plagiarism detected can help college professors check their subject and the works of the former students.
  • Self-plagiarism cases if you have more than one paper to check. It means that you may still quote something from your paper that is original, yet repeat or copy certain parts in your next assignment.

It’s a reason why plagiarism scanners must be used as supplementary tools in academic writing or blog posting but not as the primary solutions that can help rule out the final decision. Still, they still help to determine the cases of severe plagiarism when an entire or a part of the paper has been copied.

Things to Consider When Choosing Plagiarism Detection Tools

Look for those solutions that do not require registration or sharing of your personal data. The same relates to the storage of the information that you submit. This way you may get in trouble with your university as submitted assignments and information cannot be shared online, according to most university’s rules. For example, FixGerald does not store your data anywhere and lets you check through the general web content and academic databases by keeping things safe.

Now, how do plagiarism checkers work that brings out the best outcome? Pay attention to the report’s generation and the results. If you can check things again by editing highlighted parts right in the tool, it means that you’re dealing with an efficient solution!


  • Can plagiarism scanners detect originality in PDF documents?

Yes, the majority of plagiarism scanners can check the content presented in PDF documents as long as they do not contain scanned parts of the text where the words cannot be detected by the algorithm.

  • Is it reliable to use plagiarism checkers in terms of accuracy?

While plagiarism checkers can “catch” specific passages of text that have not been plagiarized, they help to detect similarities and provide a clear report that will highlight every bit of your content that may bring up concerns among college professors.

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