I work on OnePassApps, the team behind app.onepassapps.com, so this is a measurement of our own site. Everything below was measured on 9 November 2026 with plain HTTPS from one network - no session, no cookies, no JavaScript, one build, one edge.

We have written about the id layer, the class layer, the link layer, the JSON-LD identity layer and the landmark layer of these 56 pages. This one is about the layer in between: the attributes whose names start with data- .

It is the layer that says what a thing is for, rather than what it is called. Counting it whole gives a census of the fleet, and the census has a clear outlier: one page carries more of these attributes than the other 55 put together.

The census

I took every URL in our own sitemap - 56 of them - fetched each one and counted every attribute whose name starts with data- .

There are 16 distinct names across the fleet and 589 attribute instances in total.

Split them by who wrote them and the numbers get more interesting.…