Text Similarity Checker
Compare two texts and get a similarity percentage score. Measure how similar or different two blocks of text are.
About the Text Similarity Checker
Compare two text excerpts using word overlap, character trigram overlap and longest common subsequence length. The combined similarity score weights those measures at 40%, 35% and 25%. The report lists shared words and words unique to each text, helping you compare drafts or repeated wording. Word matching uses English letters and numbers; it is not a semantic comparison or an internet plagiarism search. Keep each excerpt under 20,000 characters and the product of their lengths at most 4,000,000 for the sequence calculation.
Features
- Weighted similarity percentage
- Word-set overlap with shared and unique word lists
- Character trigram overlap
- Longest common subsequence length
- Browser processing with an explicit input-size limit
How to use this tool
The Text Similarity Checker works right in your browser — no signup, no installation. Follow these steps:
- Paste the first text into the left textarea.
- Paste the second text into the right textarea.
- View the similarity percentage and detailed analysis instantly.
- Use the breakdown to understand which parts match.
Frequently asked questions
How is the score calculated?
Word-set Jaccard similarity contributes 40%, character trigram Jaccard similarity 35%, and the longest common subsequence divided by the longer input length contributes 25%. Word and trigram comparisons ignore case; the subsequence comparison retains case.
Does this highlight matching passages?
No. It lists shared and unique words and shows numerical comparisons. Use a text diff tool to inspect changed passages.
Does a high score prove plagiarism?
No. The score describes overlap between the two supplied excerpts. It does not search websites, identify authorship, or establish whether reuse is permitted.
Using the results
Good analysis needs to be both fast and private. The Text Similarity Checker processes your text locally and shows results as you work, so you can iterate on drafts and data freely, knowing the content is never transmitted or stored.