Plagiarism & Text Similarity Checker

Compare two texts for similarity using trigram matching and Jaccard coefficient. 100% client-side — your text never leaves your browser.

Disclaimer:

This is a basic client-side similarity tool using trigram matching. It is NOT a professional plagiarism detector and cannot check against the internet or academic databases. Your text never leaves your browser.

Text 1 (Original / Reference)

Text 2 (Comparison)

Text Similarity Checker — How It Works

This tool uses trigram (3-gram) n-gram matching combined with the Jaccard similarity coefficient to measure how similar two texts are. Trigrams are all consecutive 3-word sequences in a text. The Jaccard coefficient is: |Intersection| / |Union| — the proportion of shared trigrams out of all unique trigrams across both texts. A score of 0% means no common 3-word sequences; 100% means identical trigram sets. This method is robust to minor rephrasing and word order changes. A score above 40% suggests significant overlap; above 70% indicates the texts are very similar in phrasing. Note: This is not equivalent to professional plagiarism detection services like Turnitin, which compare against databases of billions of documents.