Glossary
Real user monitoring (RUM)
Measuring performance and errors from inside real users' browsers, using their actual sessions as the sample.
Also called RUM.
Real user monitoring collects measurements from the browsers of actual visitors: page load timings, resource errors, JavaScript exceptions, and increasingly the Core Web Vitals. The sample is whoever happened to visit, on whatever device and connection they had, which is both its strength and its limitation.
It answers questions no scheduled check can. Whether the site is slow on real mobile connections, whether one browser version is throwing errors, whether the ninety-fifth percentile of your Australian customers has a materially worse experience — these are facts about your user population, and only your user population can supply them.
Its blind spot is symmetrical: when nobody is visiting, RUM sees nothing, and when the site is completely down there are no browsers left to report from. An outage at 4am produces silence, which is indistinguishable from a quiet night. That is why the two techniques are complements rather than alternatives — synthetic checks tell you whether the service is up, and RUM tells you what it is like to use.
In Uptimely
Uptimely does not do real user monitoring, and none is planned. It monitors from the outside on a schedule and ingests OpenTelemetry logs, traces and metrics from your own services; neither is a substitute for measurements taken in a visitor's browser. If RUM is a requirement, it needs a separate tool.
Read next
Part of the Uptimely monitoring glossary — plain definitions of the vocabulary uptime monitoring, incident response and status pages are discussed in. Something here read wrong to you? Email support@getuptimely.com.