How to use this checker well
This is the right tool when you have the suspected source: a teacher comparing an essay against a reference, an editor checking a draft against the article it was "rewritten" from, a student verifying their paraphrase is genuinely their own words. Paste both, compare, and read the matching sentences — the percentage alone never tells the story, because properly quoted and cited passages, references lists and stock phrases ("in conclusion, the results suggest that") all match legitimately.
How the score works
The headline number is a Jaccard similarity over 5-word shingles — chunks of five consecutive words — so casual word overlap barely moves it, while copied sentences move it a lot. Sentence matches use word-overlap (Dice) scoring at a 55% threshold. As a rule of thumb: under 12% against a single source is normally just shared topic vocabulary; over 40% means large parts follow the original word-for-word and deserve a careful read.
Frequently Asked Questions
Can it check my text against the whole internet?
No — and be suspicious of free tools that claim to. Web-scale checking needs a paid index of billions of pages. This checker does the honest version: a deep comparison against the source text you provide.
Are my texts uploaded or saved?
Never. The comparison runs in JavaScript in your browser; nothing leaves the page.
What similarity percentage counts as plagiarism?
There is no universal number — context decides. A 60% match that is a quoted, cited passage is fine; a 20% match of uncited copied argument may not be. Read the matched sentences.
Can I load texts from files?
Yes — use the "Load .txt" buttons under each box.
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