Content Similarity/Plagiarism Checker

A content similarity checker compares two pieces of text to see how much they overlap. It looks at shared words, matching phrases, and overall structure to give you a percentage score showing how similar the texts are.

This tool is useful for checking if your content is too similar to something else, verifying that rewrites are different enough from the original, or spotting potential plagiarism issues before publishing.

This tool uses three different methods to measure similarity, then combines them for an overall score.

• Word Overlap (Jaccard Index). This counts how many unique words appear in both texts divided by the total unique words across both. A higher percentage means more shared vocabulary.
• Cosine Similarity. This looks at how often words appear in each text and calculates how similar those patterns are. Two texts about the same topic will score higher even if they use different phrasing.
• Phrase Matching (N-grams). This finds sequences of 3 or more words that appear in both texts. Matching phrases are a stronger indicator of copied content than individual word matches.

The overall score weights these methods to give you a balanced picture. Phrase matches count more heavily since they are harder to produce by accident.

The ideal similarity score depends on what you are comparing and why.

• 0-15% similarity. The texts are quite different. This is what you want when checking if your content is original enough.
• 15-30% similarity. Some overlap exists, usually from covering the same topic. This is often acceptable, especially for industry-specific content that naturally shares terminology.
• 30-50% similarity. Significant overlap. You should review the matching phrases and consider rewriting sections that are too close to the source.
• 50%+ similarity. The texts are very similar. If this is not intentional, you will want to substantially rewrite the content to avoid duplicate content issues.

Keep in mind that technical content, legal text, and industry jargon will naturally produce higher similarity scores. Context matters.

Yes. This tool runs entirely in your browser using JavaScript. Your text never leaves your computer or gets sent to any server. You can even disconnect from the internet after loading the page and the tool will still work.

This makes it safe to use with confidential documents, unpublished content, or any text you would rather not share with a third party service.

Traditional plagiarism checkers scan your text against a database of web pages and documents to find matches across the internet. This tool compares two specific texts that you provide.

Use this tool when you already have the two texts you want to compare - like checking a rewrite against the original, comparing drafts, or verifying that outsourced content is not too similar to a competitor's page you found.

For checking against the entire web, you would need a service with access to a large document database. This tool is meant for direct text-to-text comparison.