The Chrome UX Report lists origins, not domains. An origin is a hostname: blog.example.com and shop.example.com are two origins on one registered name. Almost every published “top websites” statistic quietly picks one of those two units and never says which.
It matters more than it sounds. The list holds 17,628,280 origins on 13,415,066 registrable domains — 4,213,214 extra hostnames, and they are not spread evenly.
12,493,699 domains contribute exactly one origin each. The other 921,367 contribute 5,134,581 between them. Count origins and you are, to a real extent, counting hosting platforms.
Where the extra hostnames live
The twenty domains carrying the most origins
Each of these is one registered name. The bar is how many distinct hostnames under it CrUX measured.
Source: Chrome UX Report top-origins list. An origin is a scheme + host; a domain is the registrable name below the public suffix.
The list reads as a history of free publishing. blogspot.com is still the largest single name on the measured web by hostname count. wordpress.com, tistory.com and substack.com are the same shape. So are the deploy platforms: pages.dev and vercel.app between them contribute more origins than most country extensions.
Which extensions the effect distorts
Divide origins by domains and you get a number that says how much of an extension is one-name-per-site and how much is a platform. .com sits at 1.32. These do not.
Origins per registrable domain
Extensions with at least 10,000 origins. A value of 1.0 would mean every domain contributes exactly one hostname.
Source: Chrome UX Report top-origins list. An origin is a scheme + host; a domain is the registrable name below the public suffix.
.pm is Saint-Pierre-et-Miquelon: population about 5,800, and 219 origins per domain. Two addresses — mp3.pm and booth.pm, a Japanese creator marketplace — carry 27,419 of its 27,590 origins. Rank extensions by origins and .pm looks busier than .lu. Rank them by domains and it disappears.
.edu at 14.5 is the honest version of the same effect: a university really does run dozens of hostnames. .io at 3.06 is github.io, and .dev at 5.12 is pages.dev.
The ranking changes
Both orderings below come from the same snapshot. Only the unit differs.
Top twelve, counted two ways
By origins on the left of each row, by registrable domains on the right. Four extensions change place.
Source: Chrome UX Report top-origins list. An origin is a scheme + host; a domain is the registrable name below the public suffix.
.de moves from third to second, .uk from eighth to fifth, and .in drops out of the twelve entirely in favour of .nl. None of that is a change in the world. It is a change in the question.
What we do about it
- Both grains, every time. Every extension figure on this site carries an origin count and a domain count. Neither is “the” number.
- Origins answer “what do people load”. If you want to know how much of the browsing web wears an extension, origins is the right unit — a reader visiting a Blogspot page really is visiting a .com.
- Domains answer “what do people buy”. If you are sizing a registry or comparing against registration counts, domains is the only unit that lines up.