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Text Similarity Checker
A text similarity checker compares two passages and scores how much they overlap, so near-duplicate pages, thin spun rewrites, and accidental boilerplate get caught before they hurt a site. Instead of eyeballing two drafts, it tokenises both texts and measures their word-level resemblance with three established algorithms, then bands the result so the answer is immediate: distinct, substantial overlap, or near-duplicate.
This tool is free and runs entirely in the browser, so two confidential drafts can be compared without either one being uploaded. It reports Jaccard similarity, cosine similarity over term frequencies, and a 3-word shingle overlap, alongside the exact counts of shared and unique words behind every score.
Shared & unique words
🔒 Private: everything runs in your browser. Nothing you paste is uploaded.
How the text similarity checker works
Paste two texts, choose whether to ignore common stopwords, and press Compare. The tool returns three independent similarity percentages and a combined verdict, with a word-level breakdown of what the two passages share.
Three algorithms, because one number hides too much
Each metric answers a different question. Jaccard similarity divides the shared unique words by the total unique words, so it measures vocabulary overlap regardless of length. Cosine similarity builds a term-frequency vector for each text and measures the angle between them, so repeated terms and emphasis count. The 3-word shingle overlap compares running three-word phrases, which catches copied sentence structure that word-set metrics miss. Reading all three together separates two texts that merely share a topic from two that genuinely reuse the same wording.
Tokenisation and the stopword toggle
Before any score is computed, both texts are lowercased, stripped of punctuation, and split into word tokens, so capitalisation and trailing commas never inflate a difference. The stopword toggle removes high-frequency function words like the, a, of, and and, which otherwise dominate the overlap and push every comparison artificially high. Turn stopwords off when exact phrasing matters, such as checking a legal clause or a quotation. Turn them on when the goal is to compare the substantive vocabulary of two articles rather than their grammatical scaffolding.
Reading the verdict band for SEO decisions
The combined verdict averages the metrics into one band: above 80% flags a near-duplicate that risks consolidation or a canonical conflict, 50 to 80% signals substantial overlap worth differentiating, and below 50% reads as distinct. These bands are a lexical guide, not a ranking verdict, because they measure shared words rather than meaning, so a paraphrase that swaps vocabulary can score low while reading as a copy. Use the shared-and-unique word lists to see exactly which terms drive the number before deciding to rewrite, merge, or canonicalise a page.
Text similarity checker frequently asked questions
Q1What counts as a near-duplicate score?
This tool treats a combined score above 80% as a near-duplicate, 50 to 80% as substantial overlap, and below 50% as distinct. Those bands are a lexical guide based on shared words, not a fixed search-engine threshold. Two pages that score high deserve a closer look for canonical conflicts or consolidation, but the decision should weigh intent and content depth, not the percentage alone.
Q2What is the difference between Jaccard and cosine similarity?
Jaccard similarity compares the unique word sets of two texts, ignoring how often each word appears, so it measures vocabulary overlap. Cosine similarity builds a frequency vector for each text and measures the angle between them, so words that repeat carry more weight. A short and a long text on the same subject can score high on Jaccard but lower on cosine, which is why this tool reports both.
Q3Is this a plagiarism checker?
No. A plagiarism checker compares your text against billions of indexed web pages over a network connection. This tool only compares the two passages you paste, using local word-overlap math, and never fetches or searches external sources. It is built for spotting duplication between drafts you already have, such as two product descriptions or a rewrite against its original, not for scanning the open web.
Q4Does the text I paste get uploaded anywhere?
No. Every calculation runs in your browser with client-side JavaScript, and neither text leaves the page. Nothing is sent to a server, logged, or stored, and the tool keeps working offline once the page has loaded. That makes it safe for comparing unpublished drafts, client material, or confidential copy that should never be transmitted to a third-party service.
Q5Why does a paraphrased copy sometimes score low?
Because these metrics are lexical, not semantic. They count shared words and phrases, so a rewrite that replaces vocabulary with synonyms and reorders sentences can read as a copy yet score as distinct. Use the shared-and-unique word lists to judge intent, and treat a low score on heavily reworded text as a prompt to read both passages rather than proof they are genuinely different.
