PathOctober 2026
Synthetic monitoring vs RUM: which sees the broken journey before your customers?
RUM describes what real users already lived. Synthetics replay the critical journey even at 3 a.m. with no traffic. To alert before complaints, you need both — and a Flow that clicks.
What RUM measures
Real User Monitoring aggregates Core Web Vitals, JS errors and real sessions. It is excellent for perf priorities and browser diversity. It needs visitors: no traffic, no signal.
After a night release with no visitors, RUM stays quiet. The checkout bug only appears with the first morning customer — too late for a sleeping team.
What synthetics measure
A scheduled probe replays login, cart or an API chain from the EU. Pathly splits Ping (HTTP), Flow (real Chrome) and Chain (chained HTTP). You see the regression before the morning peak.
Synthetics do not replace RUM: they complement it. RUM for the real distribution, Flow for continuous proof of the business journey.
- RUM = historical truth of users.
- Synthetics = continuous proof with no traffic.
- Flow = the synthetic that actually clicks.
When to choose Pathly Flow
If your risk is a button, a selector or a checkout funnel, RUM alone is too late. Record the journey once, let Flow replay it, keep RUM for overall perf.