What is Real User Monitoring (RUM)?

Real User Monitoring (RUM) is frontend observability from the user’s side of the wire: a small SDK in your web or mobile app measures what actual users experience — page load performance, interaction responsiveness, JavaScript errors, and user journeys — and streams it to your observability backend. It answers the question backend telemetry never can: what was it actually like to use the app?

Why backend monitoring isn’t enough

Your API can serve every request in 80ms while users wait six seconds for a usable page — blocked on JavaScript bundles, third-party tags, slow mobile networks, or layout thrash. Studies of the frontend experience consistently show most user-perceived latency happens after the backend response. RUM makes that invisible majority measurable.

What RUM captures

• Core Web Vitals — LCP (loading), INP (interactivity), CLS (visual stability), the metrics Google uses to score page experience
• Timings — navigation, resource loading, XHR/fetch calls, route changes in SPAs
• Errors — JavaScript exceptions with stack traces, failed network calls
• Context — browser, device, OS, geography, connection type
• Sessions — the sequence of pages and actions; session replay reconstructs it visually
• Frustration signals — rage clicks and dead clicks that flag broken UX even without errors

RUM plus distributed tracing

The most powerful setup connects RUM to backend distributed tracing: the browser’s fetch call carries a trace context header, so one trace runs from the user’s click through every backend service. Frontend symptom, backend cause, one view.

RUM in OpenObserve

OpenObserve includes frontend monitoring with Core Web Vitals, error tracking, session replay, and frustration signals — in the same platform as your logs, metrics, and traces, so frontend and backend telemetry correlate natively instead of living in separate per-seat-priced tools.