Free Plagiarism Checker — Compare Two Texts for Similarity
0% Low similarity
Matching sentences
0/0
Common words
0
Unique words (A / B)
0 / 0
Paste two pieces of text to instantly measure how similar they are. The checker computes Jaccard word-overlap similarity, counts matching sentences, and shows common vocabulary — all without sending your text to any server. Useful for spotting copied content, checking paraphrasing, or comparing drafts.
How it works
- 1 Paste your source text Enter the original text in the 'Source Text' box. This is the reference document you want to compare against.
- 2 Paste the text to compare Enter the second document in the 'Compare Text' box. This could be a student essay, a draft, or any text you suspect may overlap with the source.
- 3 Click Check Similarity The tool instantly calculates a similarity percentage, counts matching sentences, and shows how many words the two texts share.
Your data stays private
All processing happens entirely in your browser. No files, text, or data are ever sent to our servers. You can disconnect from the internet and this tool will still work.
Frequently asked questions
- How is the similarity percentage calculated?
- The tool uses Jaccard similarity on unique words: it divides the number of words found in both texts by the total number of distinct words across both texts, then multiplies by 100.
- Is my text sent to a server?
- No. All processing happens inside your browser using JavaScript. Your text never leaves your device, making it safe for confidential documents.
- What similarity score indicates plagiarism?
- There is no universal threshold. A score below 20% is generally low overlap, 20–50% is moderate (common with paraphrasing), and above 50% suggests significant shared content. Context matters — legal or academic documents have different standards.
- What counts as a matching sentence?
- Sentences are split on punctuation and then normalised (lowercased, punctuation stripped). Two sentences are counted as matching if their normalised forms are identical.
- Can I check for self-plagiarism between two drafts?
- Yes. Paste version 1 in the source box and version 2 in the compare box. The tool will show how much text you reused across drafts.