I work on OnePassApps, so this is our own site, and everything below is a measurement of our own public pages - fetched and decoded, not a guess.

When you paste a link to app.onepassapps.com into a chat app, a document, or a social post, what a reader sees before they click is not the page. It is a preview: a title, a line of description, and one image. That preview is built from tags in the page's <head> , and it is a layer of the site that almost nobody looks at.

So I looked at it. Sixteen public URLs, fetched one by one, and the preview image itself decoded pixel by pixel.

How this was measured: plain HTTPS GETs with a browser User-Agent - no JavaScript, no browser tab, no sign-in - one request per URL in the sitemap. For each page I read the Open Graph and Twitter card tags out of the <head> .…