A plagiarism checker searches databases for similarities between your text and other texts. Universities utilize them to scan student work. Pre-submission checks can also be done with commercial plagiarism detectors.


Plagiarism checkers trawl the internet and index content, comparing your text to a database of existing content. Keyword analysis highlights exact matches. Some checkers can find near-matches (paraphrasing plagiarism).


The user receives a plagiarism percentage, indicates the plagiarism, and specifies the sources. Below is an interactive view of the Scribbr Plagiarism Checker.


Sample report on Scribbr


Comparing plagiarism checkers


While most plagiarism detectors work in a similar way, there are some subtle variances that affect what they can detect.


We researched the best plagiarism checkers in 2022 to help you choose the best. Listed here are the key differences between checkers.


DB size


Not all plagiarism detectors use the same database. This can lead to significant results.


They often have smaller databases. This limits their ability to find matches, especially with less accessible online content. The best plagiarism checkers have larger databases and can find more matches.


The Scribbr Plagiarism Checker uses Turnitin’s extensive database. This database includes scientific publications, scholarly journals, and books.


Scanner quality


The scanning software itself varies greatly in quality. Many free checkers only match exact. These checkers are unlikely to notice a close paraphrase or omit a citation.


High-quality plagiarism detectors look for non-exact matches among paraphrased or altered texts.


The software scans sentences for structural similarities. Your text should be 100% original, not matching any existing document fingerprints. These checkers can detect matches.


Plagiarism checkers miss


While plagiarism checks are constantly improving, they cannot yet recognize everything.


Non-textual plagiarism


Incompletely altered or translated concepts are difficult to detect by plagiarism checkers. They also can’t help with non-text plagiarism like image plagiarism.


Translated texts, concepts, photos, or other non-text elements are still plagiarism and have the same consequences.


Internal database text


Most educational institutions have their own internal database with uploaded work from current and former students.


This database is rarely shared. This indicates that a commercial plagiarism detector is unlikely to detect student plagiarism.


However, educational institutions sometimes exchange access to their internal database with other schools to better detect plagiarism and other academic dishonesty. Replanning someone else’s work as your own is still plagiarism and carries the same penalties.


Scribbr’s Self-Plagiarism Checker will help you detect unpublished or private documents like a previously submitted paper or a friend’s thesis. To submit papers not available online but still in your university’s database, use this tool.