Plagiarism Checker
Find passages of your text that appear word for word in Wikipedia or research abstracts (OpenAlex), and compare each one with its source.
A pre-check, not a verdict. We search a sample of phrases from your text against the sources named with each result. Paraphrased copying is not detected. A low score does not mean the text is original. Scores are not comparable with Turnitin or iThenticate, whose databases are private.
What the Plagiarism Checker does
It looks for passages of your text that appear word for word, or nearly word for word, in sources it can reach: English Wikipedia and the abstracts of research papers indexed by OpenAlex. Each passage it finds is highlighted in your text and shown next to the source's own wording, with a link to the source.
The headline number is the share of your text found in those sources. It counts only the words that actually match, not whole sentences around them, and it is worked out once, on our server, from the sources found. Nothing in the result is written by an AI model.
How it works
Paste your text
Between 50 and 4,000 words (1,500 on the free plan). Your text is checked exactly as you paste it.
We search a sample of phrases
Up to 40 short phrases (8–12 words) are chosen across your text. A few spread-out phrases are searched first, as exact quotes; the rest are searched only if those find nothing. Every source found is then compared with your whole text, word by word.
Read the matches
Close matches are underlined in red, partial matches in yellow with a dashed line. Select a passage to open the source and compare the two texts side by side.
Revise, then check again
Rewrite a passage in your own words, or on the Pro plan let us suggest a rewrite. The score on screen belongs to the text you checked; run a new check to score the revised text.
What the result cannot tell you
This is a pre-check, not a verdict. Paraphrased copying, where the wording has been changed, is not detected. Because only a sample of phrases is searched, a single copied sentence can be missed, and sources outside Wikipedia and research abstracts (OpenAlex), such as books, news sites, student papers and paywalled articles, are not searched at all.
A low score does not mean the text is original, and a match is not proof of wrongdoing: quotations you have credited, common phrases and your own earlier work can all match. Scores are not comparable with Turnitin, iThenticate or CNKI, whose databases are private. Only English Wikipedia is searched for now, and research abstracts are mostly in English. Text in other languages, and text without full sentences, can't be checked yet.
Frequently asked questions
Is the Plagiarism Checker free?
Yes, you can try it without an account: guests get 1 check a day of up to 1,500 words. Signing in with your email gives you 3 checks a day, and Pro gives you 100 checks a month of up to 4,000 words. See Pricing for the current limits.
What does the percentage mean?
It is the share of your text that was found word for word, or nearly word for word, in the sources we could reach. It is not a "plagiarism score": whether a match is a problem depends on whether you quoted and credited the source.
Is this the same as Turnitin?
No. Turnitin, iThenticate and CNKI compare texts with large private databases of student papers and publications that we cannot search, so their scores and ours are not comparable. Use this tool to catch passages you may have forgotten to quote or credit before you submit.
Does it detect paraphrasing?
No. This version finds text that matches word for word or nearly so. Copying that has been reworded is not detected, and a low score does not mean the text is original.
Which sources are searched?
English Wikipedia and research abstracts indexed by OpenAlex. A few short phrases from your text (8–12 words each, up to 40 in all) are sent to those two services as search queries; the rest of the phrases are sent only if the first ones find nothing. Your full text is not sent to them.
Which languages can it check?
Only English Wikipedia is searched for now, and research abstracts are mostly in English. Text in other languages, and text without full sentences, can't be checked yet. The check needs sentences of at least 8 words to search for; if your text has none, such as a list of short bullet points, it is refused before it uses a check.
Can it rewrite a flagged passage?
On the Pro plan, yes: "Rewrite this passage" suggests a new wording of that passage, keeping numbers, links, citations and quotations as they are. It uses your rewrite allowance, the same one the AI Humanizer and AI Paraphraser use. The score is not changed by a rewrite; run a new check to score the revised text.
Do you keep my text?
Your checks are saved in your history so you can reopen them, and you can delete any entry at any time from the History panel. Our Privacy Policy explains what we store and for how long.