Check text similarity and duplicate content online free - no signup. Compare two pieces of text to find matching sentences, repeated phrases, and similarity percentage instantly.
Unintentional plagiarism happens when content is paraphrased too closely, when remembered phrases from sources bleed into drafts, or when AI-generated text reuses common phrasing. A plagiarism check before submitting prevents academic penalties and copyright issues.
Paste your text and check for duplicate content against common web sources. Highlights potentially non-original passages so you can review, cite, or rewrite them before submitting.
Check essays and papers before academic submission, verify that blog content is original before publishing, audit AI-generated content for excessive duplication, check product descriptions for content uniqueness, review freelance writing submissions for originality, and verify that repurposed content has been sufficiently differentiated.
The most common question is whether well-paraphrased content gets flagged. Advanced plagiarism detection looks for semantic similarity, not just exact phrase matches - so text that closely mirrors a source's structure and ideas can still be flagged even after rewording. Genuine rewriting with citation is the safest approach.
Paste your original text and the text to compare against.
The tool compares sentences and phrases for matches.
View the similarity percentage and highlighted matches.
Copy or download the similarity report.
Common questions about this tool and how to use it.
Plagiarism includes: copying text directly without quotation marks and citation, paraphrasing another person's ideas without attribution, presenting someone else's argument or finding as your own, reusing your own previously submitted work without disclosure (self-plagiarism, in academic contexts), and using AI-generated text without disclosure where such disclosure is required. The common thread: claiming credit for work that originated elsewhere.
Plagiarism checkers compare submitted text against a database of web pages, academic papers, and books using two approaches: exact matching (finding identical or near-identical phrase sequences) and semantic similarity (identifying passages that convey the same meaning in similar structure). Advanced checkers catch paraphrased content that exact matching would miss. Free tools typically use web crawling databases; paid academic tools (Turnitin) include proprietary academic paper databases.
Yes - modern plagiarism checkers using semantic analysis can detect content that closely mirrors a source's structure and argument flow, even when individual words have been changed. If you follow the original sentence-by-sentence, replacing words with synonyms, the paraphrase may still match. Genuine paraphrasing requires understanding the source material and expressing the idea independently - not working through it sentence by sentence.
Reduce plagiarism score by: quoting directly and citing properly rather than poorly paraphrasing, rewriting flagged sections from scratch (not just swapping synonyms), adding your own analysis and original framing around cited material, removing unnecessary citations of common knowledge, and reviewing block quotes that push similarity scores up. Do not aim for 0% - a document with proper citations will always have some similarity from quoted material.
There is no universal standard. Most universities set thresholds of 10–25% overall similarity (excluding properly cited quotes and references sections). A 15% score that is all properly cited quotations is fine; a 5% score from an uncited paragraph is plagiarism regardless of the total. The composition of the similarity matters as much as the percentage. Check your institution's specific plagiarism policy for the threshold that applies to your submission.
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