Free Duplicate Content Checker
Paste two blocks of text to see a similarity score and exactly which sentences overlap, so you can tell whether a rewrite is different enough or still reads as duplicate content to Google.
- Sentence-level overlap detection
- Similarity percentage
- Runs entirely in your browser
Two texts to compare
Duplicate Content Checker
Similarity report
Generated result
Paste both Text A and Text B to compare.
Where this tool fits
How to use the duplicate content checker
How the similarity score is calculated
The checker splits both texts into sentences, normalizes whitespace and punctuation, and matches sentences that are identical or near-identical after normalization. The similarity percentage is the share of Text A's sentences with a match in Text B — it's a practical overlap measure, not Google's internal duplicate-detection algorithm, which nobody outside Google has access to.
What counts as duplicate content in practice
Google rarely penalizes duplicate content directly; more often it just picks one version to rank and ignores the other, or folds them into one cluster in search results. The risk is highest on templated pages (multi-location sites, syndicated articles, boilerplate product descriptions) where dozens of pages share the same paragraph with only a name or city swapped.
A high score isn't automatically bad
Boilerplate like legal disclaimers, safety warnings, or a recipe's fixed ingredient list is expected to repeat and isn't the problem. Focus on the body content that's supposed to be unique per page — if that's what's scoring high, that's the part worth rewriting.
Duplicate Content Checker FAQ
Is the duplicate content checker free?
Yes. The duplicate content checker is free to use on Seobase with no signup required for the on-page duplicate content check.
Can I use the duplicate content checker for SEO content?
Yes. The tool is built for search-focused workflows and pairs best with human review before publishing.
Does Google penalize duplicate content?
Usually not with a direct penalty. Google typically consolidates duplicates and shows only one version in results, which means your intended page may simply not be the one that ranks. The practical fix is the same either way: make the page's unique content substantial enough to stand alone.
Does this check my page against the whole live web?
No — it compares two texts you paste, entirely in your browser. It can't tell you whether a page duplicates something elsewhere on the internet; use a web-wide plagiarism tool for that. This is built for comparing a rewrite against its source, or one templated page against another.
How much similarity is too much?
There's no official threshold. As a practical guideline, treat anything above roughly 30-40% sentence overlap in your main body content (excluding boilerplate) as worth a rewrite pass, especially if the pages are meant to target different queries.
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