Methods
Lighthouse
Google's open-source tool that audits a page in a lab run and scores performance, accessibility, SEO and more.
Lighthouse loads a page under simulated conditions and produces a 0 to 100 performance score from lab metrics like FCP, LCP, TBT, CLS and Speed Index, plus concrete recommendations. It powers the lab side of PageSpeed Insights.
fastmon's synthetic checks run Lighthouse on a schedule so you get its diagnostics continuously, not just when someone happens to run an audit.
Related terms
- RUMReal User MonitoringMeasuring performance from the browsers of your actual visitors, on their real devices and networks.
- Synthetic MonitoringScheduled, repeatable tests that load a page in a controlled environment on a fixed interval.
- Lab data vs field dataLab data comes from a controlled test; field data comes from real visitors. Both matter, for different reasons.
- CrUXChrome UX ReportGoogle's public dataset of real-world Core Web Vitals, aggregated from opted-in Chrome users.
- p75Percentile (p75)The value below which a given share of visits fall. p75 means 75 percent were at least this fast.
- Web Vitals AttributionThe extra diagnostic data that explains why a metric was slow, not just how slow it was.
- Web AnalyticsTraffic and behaviour measurement: page views, visitors, referrers and journeys, alongside performance.
- Error TrackingCapturing JavaScript errors and failed requests from real sessions, grouped so you see the real problems.
- AlertingNotification rules that tell you when a metric breaches a threshold or degrades, before customers complain.
Monitoring that
belongs in the EU.
Read-only by default: no cookies*, no long-lived identifiers, no US provider in the data path. Live in about five minutes.
Light
€29/month
200,000 pageviews included.
Need debugging and all features? Standard from €99 for 1M pageviews. Enterprise on request. See all plans