Ranked by adoption
Six adoption tiers
Every term falls into a domain-count bucket. Sorted from most adopted to least, the bottom tier (fewer than 1,000 domains) holds more terms than all five other tiers combined.
Bar length ∝ √(number of terms), rescaled per view. Counts are unique domains, not pages or URLs.
The head of the curve
The most-used terms
The most-adopted terms are structural and commercial: breadcrumbs, websites, organizations, products, offers, ratings, articles. These are the terms found on the widest range of domains across the web.
Types
top 47Used by 10M+ domains · 12
Used by 1M–10M domains · 35
Properties
top 96Used by 10M+ domains · 31
Used by 1M–10M domains · 65
The reality check
The long tail
This curve doesn't measure what's useful. It measures what Google rewards.
We mark up what earns rich results and ignore the rest. Of Schema.org's 4,587 properties, 3,779 sit below a thousand domains; most of the vocabulary describes things no rich result depends on. Even the well-known rich-result types rank in the middle of the table, well below the structural and commerce terms:
All 5,545 terms
Explore the full dataset
Search any term, filter by kind or adoption tier, sort by name or popularity. Each term links to its Schema.org definition.
Read before you cite
How to read this data
Domains, not pages
A term is counted once per domain. Product used on 100,000 pages of one site still counts as a single domain, so the number reflects how many sites use a term, not how often it appears.
Formats are merged
JSON-LD, Microdata and RDFa are counted together. The data does not say which syntax a site used to write a term.
Google's index only
These are counts from Google's public crawl. Sites blocked in robots.txt are not included, and the numbers reflect what that crawler sees.
Small does not mean unused
A low count is not always low value. Medical and government terms serve a narrow part of the web, so they sit in the lower tiers even when they are standard within their field.
Each tier is a range of unique domains, not an exact count. Grouping this way smooths daily crawl noise and protects site privacy.
Where it goes next
A living, open dataset
The dataset is refreshed every month, and its format is open for anyone to use or extend.
Refreshed monthly
A new snapshot is published to GitHub each month, after manual validation. Adoption changes slowly, so one snapshot is enough to see roughly where a term stands.
Open to other crawlers
The format is documented and not tied to one provider. Other search engines and web archives can publish their own counts in the same structure, which would extend the picture beyond a single crawler.
Built to act on
Use it to see which markup has real reach, and to check SEO tools and plugins against published adoption numbers instead of guesswork.