What it means
Inventory indexation is the process of deciding which of your product or listing pages search engines should crawl and include in their index. It treats your pages as inventory (supply) and asks which ones earn a place, rather than assuming every page will. Kevin frames marketplace SEO as optimizing a site based on its inventory, and getting the right pages indexed protects crawl budget and content quality.
Why it matters
Google indexes only about a third of the pages it finds, and pages that get in can be dropped just as fast. A bloated index of thin or duplicate pages wastes crawl budget on pages that will not rank and dilutes the quality signal for the ones that could. Kevin's point in the SEOzempic Growth Memo issue is that you do not always need more pages to grow: Often you improve the inventory you already have.
Say a mid-market marketplace has 80,000 listing pages, but 40% are near-empty or duplicated. After the team prunes and consolidates them to 45,000 substantive listings, the share of indexed pages that earn impressions climbs from 22% to 55%.
How to use this knowledge
Audit your page inventory and separate the pages that earn impressions from those that only consume crawl budget; Kevin recommends a monitoring system to read domain quality first. Prune, consolidate, or noindex thin and duplicate pages so the index reflects your best supply. Make each page you keep thorough, since a category page with 240 products competes better than one with 12. Speed up discovery with indexing APIs or IndexNow instead of waiting on crawl.
Growth Memo guidance
You do not always need to add more pages to grow. Often, you can improve your existing page inventory, but you need a monitoring system to figure this out in the first place. — SEOzempic
Google is very choosy and indexes only 1/3 of the pages it finds in a sample of 16 million over 5 years, but since 2023, it has been indexing more and more (>50% in 2025). — March news
A category page with 12 products competes badly against one with 240. — What to do now that AIOs turned search into reading sessions
Crawl budget — the finite crawl capacity you protect by keeping low-value pages out of the index.
Indexing APIs and IndexNow — ways to push the pages you want indexed to search engines instead of waiting to be crawled.
Page pruning — removing or consolidating thin pages so what stays indexed is higher quality.
Topical authority — grows when your indexed pages cover a topic in depth instead of spreading thin.