Text similarity checker for two texts
Paste two pieces of writing and this text similarity checker measures how much they overlap by comparing every three-word phrase.
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Your text stays in your browser. Nothing you paste is uploaded or stored.
How to use the text similarity checker
- Paste the first text into the left box.
- Paste the second text into the right box.
- Press Compare texts.
- Read the phrase overlap and Jaccard scores, the number of shared phrases and up to six examples.
How the text similarity checker works
The checker breaks each text into lowercase words and lists every run of three consecutive words, called a phrase or trigram. Comparing phrases rather than single words shows when wording has been reused, because common words such as the and is appear in almost any text.
It reports two scores. Phrase overlap divides the shared phrases by the number in the shorter text, so it shows how much of the shorter text appears in the longer one. Jaccard similarity divides the shared phrases by all distinct phrases in both texts, so it is lower when the texts differ in length. The tool compares only the two texts you paste. It does not search the internet and is not a plagiarism checker.
Formula
Phrase overlap = shared phrases ÷ phrases in the smaller set. Jaccard similarity = shared phrases ÷ (phrases in A + phrases in B − shared phrases).
Example
"The quick brown fox jumps" has three phrases: the quick brown, quick brown fox and brown fox jumps. "A quick brown fox runs" also has three: a quick brown, quick brown fox and brown fox runs. They share one phrase, quick brown fox.
Phrase overlap is 1 ÷ 3, about 33.3%, and Jaccard similarity is 1 ÷ (3 + 3 − 1), which is 20%.
Tips and common mistakes
Rewording is not citing
If a high overlap comes from a source you used, quote and cite it. Our paraphrasing tool can help with rewording, but you still need to credit the ideas.
Short texts give jumpy scores
With only a few phrases, one shared phrase moves the score a lot. Compare whole paragraphs rather than single sentences.
Formatting changes don't hide wording
Capitals, punctuation and line breaks are ignored, so changing them alone won't lower the score.
Check the lengths first
The word counter shows how long each text is, which helps you read the two scores together.
Frequently asked questions
Is this a plagiarism checker?
No. It only compares the two texts you paste. It can't tell whether text was copied from a website, book or another person.
What counts as a high score?
There is no universal threshold. Texts on the same topic written independently usually share few three-word phrases, so a large overlap suggests shared wording.
Why compare three-word phrases?
Single words match too easily, while long phrases miss small edits. Three words is a common balance for spotting reused wording.
Are my texts uploaded?
No. The comparison runs entirely in your browser and nothing is stored.