Core Web Vitals

Core Web Vitals reduce page experience to three field measurements: Largest Contentful Paint (loading), Interaction to Next Paint (responsiveness) and Cumulative Layout Shift (visual stability). They are computed from real Chrome users, not lab crawls.

The Chrome UX Report (CrUX) is where the numbers live. Its records carry the tags 'core-web-vitals', 'lcp', 'inp', 'cls' and 'page-experience', and its distribution shape matters: instead of a single average, CrUX publishes traffic-weighted histogram bins plus a 75th-percentile value per origin or URL - Google evaluates sites against the p75, not the mean.

Teams benchmarking site quality - media products, streaming platforms, ad-tech vendors - need field data with known distributional assumptions, and CrUX is the reference implementation.

• Averages hide the tail. Because CrUX reports p75 percentiles and full histogram bins, any tool that quotes you a single mean is discarding exactly the information the metric was designed around.
• Origin versus URL scope changes conclusions. A homepage can pass while product pages fail; check the scope key before comparing vendors.
• Access is genuinely free. 574 of the 1,744 datasets Datadory catalogs offer an official API, and CrUX ships two of them (API plus History API) alongside monthly BigQuery exports.

1. Demand the p75, not the average. CrUX's own reporting unit is the 75th percentile per origin or URL; a vendor selling means has already lost the signal.

1. Ask for histogram bins. Traffic-weighted bins show how many real users hit the 'good' threshold - a single score cannot.

1. Confirm population coverage. CrUX reflects Chrome users only; populations thin enough to fall below reporting thresholds simply have no row.

1. Check history depth. Monthly BigQuery tables reach back to 2017, so trend claims should match that window.

1. Mind rate limits when automating. Public catalog APIs meter anonymous callers - see the related entries below for how demo keys cap throughput.

Concepts that sit next to Core Web Vitals work: - api rate limits — Public catalog APIs meter anonymous use through demo keys and grant higher throughput to registered ones. - attribution requirement — A license clause conditioning reuse on visible credit, whether a live hyperlink, a named data-source citation or a linked project reference.