Compare two passages locally in your browser to see how similar their wording is.
The Text Similarity & Originality Checker compares two passages of text you provide and reports how similar their wording is, sentence by sentence, using local text-matching logic that runs entirely in your browser. This is different from a commercial plagiarism-detection service that scans billions of indexed web pages and academic databases — this tool cannot check your writing against the internet or any external database, since it never sends your text anywhere. What it can do well is a task students genuinely need often: comparing your current draft against an earlier draft, a source document, or a classmate's version (with permission) to see exactly which sentences are too close in wording and should be paraphrased further.
To use it, paste one passage into the "Text A" box and a second passage into "Text B," then press "Compare Texts." The tool breaks both passages into sentences and compares each sentence in Text A against every sentence in Text B using a word-overlap similarity measure. Sentences that share a very high proportion of the same words are flagged as closely matching, and an overall similarity percentage is calculated across the whole document based on how much of Text A's content overlaps with Text B.
This is especially useful when revising a paraphrase: after rewriting a paragraph from a source in your own words, paste your original notes as Text A and your rewritten paragraph as Text B to check that your phrasing has moved far enough away from the source's exact wording, rather than just swapping a few synonyms. It is equally useful for comparing two drafts of your own essay to see how much you actually changed between revisions, or for group projects where teammates want to confirm that sections written independently do not unintentionally overlap.
The similarity score should be read as a guide rather than an official verdict. A high score does not automatically mean misconduct, and a low score does not guarantee a passage is properly cited — proper citation of ideas and direct quotations is still required by academic integrity policy regardless of how differently something is worded. For a final check before submission, use your institution's official plagiarism-detection service (such as Turnitin or a library-provided tool), since those systems compare against enormous databases of published work that this local tool has no access to.
Because the comparison runs entirely as JavaScript in your browser, neither passage is uploaded, logged, or stored anywhere, which makes it safe to paste sensitive drafts, unpublished research notes, or another student's text (shared with their consent) for a private, one-off comparison.
It is also a useful teaching tool for understanding what over-reliance on a source actually looks like at a sentence level: running your own first draft against your source notes often reveals, in a very concrete way, how closely early drafts can mirror the original material before revision, which can make the abstract instruction to 'paraphrase more' feel much more actionable.
If you are comparing your own paraphrase against original source material you did not write yourself, remember that even a low similarity score does not remove the requirement to properly cite the original author's ideas; originality of wording and proper attribution of ideas are two separate academic integrity requirements, and this tool only addresses the first of the two.
No. This tool only compares the two passages you paste against each other locally in your browser. It does not search the web or any academic database.
No, this is a self-check tool for comparing two specific texts you already have. For an official plagiarism report against published sources, use your institution's required detection service.
It reflects the proportion of words and phrasing shared between the two passages based on sentence-level comparison. Treat it as a rough guide to how close the wording is, not a legal or academic determination.
The comparison looks at shared words rather than meaning, so two sentences that say the same thing in completely different words may score low even though the idea is the same. Always cite ideas properly regardless of wording.
No. Everything is processed in your browser's memory only and is discarded when you leave or refresh the page.
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