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SEO Madmanby Adam Hafez
Free tool

Keyword cannibalization checker

Compare titles or H1s across your own pages and flag near-duplicate pairs using Jaccard word-overlap similarity, entirely in your browser.

Runs entirely in your browser. Nothing you enter is uploaded, logged or stored.

Pages to compare
Flagged pairs

Key takeaways

  • Cannibalization is SEO-industry jargon that Google itself does not officially use.
  • The similarity score is computed with Jaccard similarity, the size of the intersection of significant words divided by the size of their union.
  • Google's real guidance covers canonicalization and duplicate content, where its own systems choose which of your competing pages to show.
  • The 50 percent default threshold is this tool's own heuristic and not a number Google has published anywhere.
  • All comparison happens in your browser, so no title or URL you enter is ever sent anywhere.

What it takes

  • A URL for each page you want to compare
  • The title or H1 text for each page
  • A similarity threshold, adjustable from 10% to 90%

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How to use it

  1. 1Add your pagesEnter the URL and the title or H1 for each page you suspect overlaps in topic. Four example rows are prefilled so you can see the tool working before you replace them.
  2. 2Set a thresholdThe slider defaults to 50%, this tool's own heuristic rather than a figure Google has published. Lower it to see more borderline pairs, raise it to see only the closest matches.
  3. 3Read the flagged pairsEvery pair scoring at or above the threshold is listed with both URLs, both titles, and the similarity percentage, sorted from most to least similar.
  4. 4Decide what to do with each pairA high score means the titles share most of their significant words, not that Google is definitely splitting ranking signals between the two pages. Check search results for your target query before merging, redirecting or rewriting anything.

Two pages on the same site can end up chasing the same query without anyone deciding that on purpose: a new post gets written, an old guide never gets updated, and both sit in the index with titles that say almost the same thing. This tool compares the titles or H1s you enter and scores how much significant wording they share, so you can spot the pairs worth a closer look before you merge, redirect or rewrite anything.

How the similarity score works

Each title is lowercased, stripped of punctuation, and split into words. A small, deliberately non-exhaustive English stopword list, words like “a”, “the”, “and”, “of” and “for”, is removed from each side, because these carry no topical signal and would inflate every score. What is left is a set of significant words for each title.

Jaccard similarity is then the size of the intersection of the two sets divided by the size of their union, expressed as a percentage. Two titles that share every significant word score 100%. Two titles that share none score 0%. A pair like “Best running shoes for 2026” and “Top running shoes: 2026 review” shares “running”, “shoes” and “2026” out of a combined set of six significant words, a worked example the tool’s own prefilled rows demonstrate directly.

Cannibalization is jargon, canonicalization is the real mechanism

“Cannibalization” is a term the SEO industry uses, not one Google’s own documentation uses. What Google has actually published, in its guidance on consolidating duplicate URLs, is that when several pages on a site are similar enough, its systems select one canonical URL to show for a given query and may fold the others’ signals into it. Which page gets chosen is decided by Google’s own systems, not by which one you intended to rank.

That is the real, citable mechanism behind the industry term. No Google document states a title similarity percentage that defines when this happens, so treat any number, including the 50% default in this tool, as a heuristic for where to look, not a threshold Google enforces.

Run the check periodically as new pages are published, since overlap tends to build up gradually rather than appear all at once.

Sources

  1. 1.Consolidate duplicate URLs - Google Search CentralPrimary
  2. 2.How Search organizes information - Google Search Central

Frequently asked questions

Is cannibalization an official Google term?

No. It is SEO-industry jargon for two pages competing for the same query. Google's own documentation talks about duplicate content and canonicalization instead, where its systems pick one URL to represent a set of near-identical pages in results.

Why Jaccard similarity and not something more advanced?

Jaccard similarity on significant words is simple, explainable and fully computable in the browser. It measures literal word overlap in a title, not meaning, so it is a starting signal for a manual check, not a ranking prediction.

Does the threshold come from Google?

No. Google has never published a similarity percentage that defines when two pages compete for a query. The 50% default here is this tool's own configurable heuristic, adjust it to match how strict you want the check to be.