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PureStats documentation

Core Web Vitals and real user monitoring

Measure LCP, CLS, INP, FCP and TTFB from real visits while respecting PureStats privacy controls.

PureStats measures page performance from real visits with Google's official web-vitals library. Open More → Performance in a site's analytics navigation to review field measurements for LCP, CLS, INP, FCP and TTFB.

What is collected

Each sample contains the metric name, value, rating, page path, navigation type and the already detected device and browser. Reports show P50, P75 and P95 values. P75 is the primary value used for the Google rating.

PureStats does not collect DOM content, resource URLs or performance traces for Core Web Vitals. Measurements follow the site's existing consent mode, Do Not Track choice, path exclusions and bot-traffic rules.

Enable or disable collection

Web Vitals are enabled by default for new and existing sites. A site owner or manager can change this under Site settings → Privacy → Data collection. The setting is delivered through the tracker configuration, so the standard tracking snippet does not need another data attribute.

Optional tracker module

The core tracker remains under 7 KB compressed. After the server setting allows collection, it loads pf-vitals.min.js as a separate optional module. When a first-party proxy is used, proxy this file in addition to the core tracker:

/pf.min.js         → https://purestats.io/pf.min.js
/pf-vitals.min.js  → https://purestats.io/pf-vitals.min.js
/api/tracker-config → https://purestats.io/api/tracker-config
/api/event          → https://purestats.io/api/event

Both JavaScript files can be cached for one hour. API responses must not be cached.

Reading the report

  • P50 describes the median visit.
  • P75 is the primary field-quality threshold.
  • P95 surfaces severe slow-tail experiences.
  • Pages needing attention lists page and metric combinations outside the good threshold.
  • Device, browser and navigation tables help isolate environment-specific regressions.

New samples appear immediately in the report. Daily percentile rollups are refreshed hourly for operational and long-term reporting.