Text Similarity Checker

Compare two pieces of text and see how much they overlap. The tool gives a combined score, word overlap, cosine similarity, the number of shared words, and a list of shared three-word phrases. It compares the words used, not the meaning, so it's a helpful signal but can't prove copying.

How to use it

1. Paste the first text.
2. Paste the second text.
3. Read the similarity score.
4. Look at the shared phrases.

When it helps

• Checking two drafts of the same document.
• Comparing a rewrite with its source.
• Spotting repeated content across pages.
• Teaching how text comparison works.

Good to know

• Common words raise the score slightly, so look at the shared phrases too.
• Paraphrased text can mean the same thing but score low.
• Use it as a first check, not as proof.

The two measures behind the score

Jaccard similarity looks only at which different words appear in each text: the number they share divided by the number in either. It ignores how often a word is used. Cosine similarity treats each text as a list of word counts and measures how closely the lists point in the same direction, so repeated words matter.

The combined score weighs cosine at 60 percent and Jaccard at 40 percent, which tends to reflect what people mean by "similar" better than either measure alone.

Worked example: two versions of a sentence

"The quick brown fox jumps over the lazy dog" and "A quick brown fox leaped over a lazy dog" share quick, brown, fox, over, lazy and dog. The score lands in the "very similar" range even though the sentences aren't identical, which is what you'd expect.

Try a rewrite of your own paragraph. If the score stays high and the shared three-word phrases are long, you've probably kept too much of the original wording.

Limits to remember

The tool can't tell whether text was copied, only that it overlaps. Two pieces on the same topic will share many words naturally, and quoted material will raise the score. Conversely, a clever paraphrase can have the same ideas and a low score.

For academic or professional integrity checks, a dedicated service that compares against large databases is a better choice. For your own drafts, it's a quick, private way to see how much two versions differ.

Using similarity for editing

Compare your latest draft with the previous one to see how much has changed. A score near 100 percent means you've barely edited, while a low score means a substantial rewrite. It's a useful check when a reviewer asks you to revise.

You can also compare two product descriptions on different pages, to find duplicates that might confuse search engines.

Reading the shared phrases

Long shared phrases matter more than many shared single words. A handful of identical five-word runs suggests copying or heavy reuse, while many shared common words simply reflects the same topic.

Questions