Plagiarism Checker
Compare your draft against public sources to catch unintentional overlap. Not a substitute for citing properly; a safety check before you submit.
How to use this
Paste the finished draft, or the paragraphs you are least sure of, after you have added your citations. The checker compares your phrasing against public sources: published essays and study guides on the works students most often write about, encyclopaedia entries, and the text of the works themselves where they are out of copyright. It returns the passages that overlap, with the likely source, so you can see whether each one is a properly quoted line, a paraphrase that stayed too close, or a sentence you did not realise you had absorbed from a guide.
Read each match and decide what it is. A quotation from the primary text inside quotation marks with a citation is fine and expected; the checker will show it because it matches, not because it is a problem. A paraphrase that keeps the source's sentence shape and swaps a few words is the one to fix: either quote it and cite it, or close the source and write the idea again in your own words from memory. A sentence that matches a study guide word for word, with no citation, is the case the tool exists for, and the fix is the same.
Use it as the last check before submission, once, not as a loop to run until the number reaches zero. The widget on this page is a preview: until the full version ships, the result panel shows a worked example of the overlap report rather than a scan of your draft.
Important caveats
A low overlap score is not proof of originality and a high one is not proof of plagiarism. The checker only sees the sources it can see. It cannot compare your draft against a classmate's essay, a paid essay bank behind a login, a printed study guide that was never put online, or your own earlier submission, and the checker your school runs may search all of those. An idea taken from a source without credit is plagiarism even when the wording is entirely yours, and no string-matching tool can detect that; only citing your sources can prevent it.
Matches will include things that are not problems. Quoting the text is required, common phrases recur in every essay on a work, and a title or a character's name will match everything. Judge each flag; do not reword a correctly cited quotation to make a percentage fall, which turns an honest citation into a misquotation.
The tool is not a way to disguise copied work, and rewording a source until the checker stops noticing is still plagiarism under every academic integrity policy we know of. Use it to catch accidents, cite what you used, and read Essay Craft for the habits, note-taking with page numbers and paraphrasing from memory, that keep the accidents from happening in the first place.