Cannibalization is what happens when several pages on one site target the same search intent. Instead of one strong page, the site fields three mediocre ones that compete with each other for the same result.
How it happens without anyone deciding to do it
Nobody sets out to publish four pages about the same thing. It accumulates: a blog post in 2022, a landing page in 2024, a category description that drifted toward the same topic, and a guide nobody remembered existed.
What the checker does
It takes a list of pages alongside their target keywords and flags where the targets overlap, so the collisions surface as a list rather than as an unexplained ranking problem.
Why the fix is usually consolidation
Merging competing pages into one and redirecting the others concentrates the signals that were being split. The combined page frequently outranks anything the separate versions managed alone.
Try it: Keyword Cannibalization Checker on SeoWolf's Notepad.