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Surfilby Adam Hafez
Free tool

Keyword cannibalization checker for page titles and H1s

Keyword cannibalization checker: compare titles or H1s across your pages and flag near-duplicate pairs by word overlap. Free, runs 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 for your own pages competing for one query, and Google's documentation does not use the term.
  • The score is Jaccard similarity, the shared significant words in two titles divided by all the significant words across both.
  • Google's documented mechanism is canonicalization, where it groups pages with similar content and picks one representative URL.
  • 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 checker compares the titles or H1s you enter and scores how much significant wording each pair shares, so you can find the pairs worth a closer look before you merge, redirect or rewrite anything.

What the checker measures

Each title is lowercased, stripped of punctuation and split into words. A short, deliberately incomplete English stopword list is then removed: a, an, the, and, or, of, to, for, in, on, with, is, are, was, were, be, by, at, as, it, this, that, your, you, how, what, why and vs. Those words carry no topic and would inflate every score. What remains is a set of significant words per title, with repeats counted once.

The score for a pair is Jaccard similarity: the number of words both sets share, divided by the number of distinct words across both, as a whole percentage. Identical word sets score 100%. Titles with nothing in common score 0%. Every pair of rows is compared, so 10 pages produce 45 comparisons. A row needs both a URL and a title to be included.

How to read the results

The “Flagged pairs” panel lists every pair at or above the threshold, highest score first, with both titles and both URLs. If none qualify it says “No pair reaches 50% similarity” (or whatever the slider is set to), and with fewer than two complete rows it asks for more pages.

A flagged pair is a question, not a verdict. Search the query both pages seem to target and see what Google shows. If one page consistently appears and the other never does, Google may be treating them as one topic already. If both pages serve different intents, such as a buying guide and a review, the overlap may be fine. If they really are the same page twice, consolidate: Google’s canonicalization guide lists redirects, rel=“canonical” and sitemap inclusion as the ways to state which URL you prefer, while noting Google may still choose differently.

Worked example

The checker opens with four pages:

URLTitleSignificant words
/blog/best-running-shoesBest running shoes for 2026best, running, shoes, 2026
/blog/top-running-shoes-reviewTop running shoes: 2026 reviewtop, running, shoes, 2026, review
/guides/trail-running-shoesA guide to trail running shoesguide, trail, running, shoes
/blog/marathon-training-planMarathon training plan for beginnersmarathon, training, plan, beginners

The first two titles share running, shoes and 2026, 3 words out of 6 distinct ones, so they score 50% and are the one flagged pair at the default threshold. The first and third share 2 of 6 words (33%), the second and third 2 of 7 (29%). The marathon page shares nothing with any of them. Drop the slider to 30% and the 33% pair appears. At 25% all three shoe pages are flagged against each other.

What Google documents

“Cannibalization” is an industry term, not one Google uses. What Google does document is how it handles similar pages. During indexing it groups pages it found with similar content, then selects the one that is most representative of the group as the canonical, the page that may be shown in results. Its canonicalization guide adds that Google picks the page it judges most complete and useful, crawls that one regularly, and crawls the duplicates less often.

That guidance is about duplicate and near-duplicate content. Two distinct articles with similar titles are not necessarily duplicates, and no Google document states a title similarity percentage at which pages start to compete. That is why this checker reads only titles or H1s, which you supply, and why its threshold is labeled as its own. Google also says some duplicate content on a site is normal and not a spam policy violation.

Common overlaps it surfaces

  • Year refreshes published as new posts. A “2026” version beside the older article, both left live.
  • The same topic in two sections, such as a blog post and a guide with near-identical H1s.
  • Listicle and review pairs built around the same product keyword.

Sources

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

Common questions

How do I check for keyword cannibalization?

List the pages you suspect overlap, with each page's URL and its title or H1, and set a threshold. The checker compares every pair and lists those whose significant words overlap at or above it. Then search the target query yourself to see which of your pages Google actually shows before changing anything.

Is cannibalization an official Google term?

No. It is SEO-industry jargon for two of your pages competing for the same query. Google's documentation talks about duplicate content and canonicalization instead, where its systems group pages with similar content and choose one representative URL.

Is duplicate content on my own site a penalty?

Google says some duplicate content on a site is normal and not a violation of its spam policies. Its concern is that duplicates make for a poor user experience and make performance harder to track, which is also why overlapping pages are worth consolidating.

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 adjustable heuristic. Move the slider between 10% and 90% to match how strict you want the check to be.

Why Jaccard similarity and not something more advanced?

Jaccard similarity on significant words is simple, explainable and computable in the browser. It measures literal word overlap in a title, not meaning, so "cheap flights" and "budget airfare" score 0%. Treat it as a starting signal for a manual check, not a ranking prediction.