Duplicate Content Finder
Compare many pieces of text at once and find the near-duplicates, with a straight answer about what duplication costs.
About this tool
Compares a set of documents against each other and reports which pairs are near-duplicates, with the overlapping passages named.
**There is no duplicate content penalty**, and any tool implying otherwise is wrong. What actually happens is that search engines pick one version and ignore the others — so the cost is that your own pages compete and the traffic lands on whichever one was chosen, which may not be the one you would have picked. That is a real cost and it is a different problem from a penalty, with a different fix.
**This is not a plagiarism checker.** It compares the documents you paste against each other and against nothing else. Two pages about the same product are similar because the subject is the same, and only a person can tell that apart from copying.
Comparison is by shingles — overlapping runs of five words — which catches reordered paragraphs and lightly edited text. Word-frequency comparison misses both, because the words are the same either way.
Common questions
Is duplicate content penalised?
No. Google has said repeatedly that there is no penalty for it. What happens is that one version is chosen and the others are filtered from results — so your pages compete with each other, and the winner is not necessarily the one you wanted.
What counts as too similar?
There is no threshold anybody publishes. As a working guide, above 80% the pages are interchangeable and should probably be one page; 50 to 80% usually means shared boilerplate rather than duplicated content.
How do I fix it?
Merge the pages and redirect one, or make them genuinely different. A canonical tag is the right answer only where the duplication is unavoidable — a printable version, a URL with parameters.
Why shingles rather than word frequency?
Because two documents with the same words in a different order have identical word frequencies and are not the same document. Comparing runs of five consecutive words catches reordering and paraphrase, which is what near-duplication actually looks like.