Building blocks
Server-Timing
An HTTP header your backend can send to break down where server time was spent, visible in RUM.
TTFB tells you the server was slow, but not why. With the Server-Timing header your backend can report its own phases (database, cache, rendering) and the browser exposes them to the tracker.
That connects a slow field TTFB to the exact backend step responsible, closing the gap between frontend symptom and backend cause.
Related terms
- BeaconThe small data packet the tracker sends to fastmon with a visit's measurements.
- TrackerThe lightweight script you embed once; it measures Core Web Vitals and errors directly in the browser.
- Stitchfastmon's short-lived, edge-derived identifier that groups a visit without cookies or cross-site tracking.
- SessionOne continuous visit: the sequence of page views and interactions a visitor makes before going idle.
- PageviewA single page load or, in a single-page app, a route change counted as its own view.
- Collection modesPresets (Light, Standard, Full) that decide how much detail the tracker collects.
- Cache-StatusWhether a response came from a CDN edge, the origin server or the browser cache.
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.
fastmon One
€99/month
1M pageviews included.
More volume, longer retention or a contract of your own? Enterprise on request. See all plans