RUM
Real User Monitoring — tracking performance as experienced by actual users in their browser.
Definition
Real User Monitoring (RUM) collects performance and error data from real users' browsers or mobile apps as they interact with a web application. Unlike synthetic monitoring, which simulates user journeys from controlled environments, RUM captures the actual experience of every real session.
In depth
RUM data includes Core Web Vitals (LCP, FID/INP, CLS), JavaScript errors, resource load times, and navigation timings. Because RUM reflects real-world conditions — varying network speeds, device types, geographic locations, and browser versions — it reveals performance issues that synthetic tests miss. Combining RUM with backend traces creates end-to-end visibility: a slow LCP can be correlated with a slow API call, which traces back to a slow database query on the server side. obseria.io's RUM integration captures Web Vitals, session context, and browser errors with automatic correlation to backend traces via W3C Trace Context headers.
Related terms
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