Synthetic vs real-user (RUM) monitoring: what is the difference?
Two approaches are often combined when monitoring user experience. Synthetic monitoring runs predefined tests that follow key journeys through the system at regular intervals—even when no one is currently shopping. Real-user monitoring (RUM) measures how the website behaved for actual visitors using data from their browsers. The RUM result depends on the implementation, sampling and quality of the data collected. Each approach answers a different question and captures different phenomena.
A common problem: one type of monitoring shows only part of the picture
A business has analytics or an uptime check installed and believes that “monitoring is covered”. Those tools, however, answer only part of the question, leaving the more important part unseen.
RUM may show that some visitors experienced a payment problem—but only after real traffic has passed through the monitored journey. The breadth of the picture also depends on sampling, consent and the data the implementation actually collects. If no one shops at night, RUM may have no new data for the purchase journey during that period, even though a version that breaks the basket was deployed at that very time.
How synthetic monitoring and RUM complement each other
Synthetic monitoring is proactive. It does not wait for a customer—a browser follows the agreed journey at regular intervals. If a step fails, an alert can arrive even when there is no traffic; detection time depends on the interval, confirmation runs and service configuration. It also captures situations that server-availability monitoring alone may miss.
RUM is reactive and complementary. It measures real performance and behaviour on actual devices and networks—figures that synthetic checks from a handful of monitoring runs cannot provide. It is excellent for showing trends and actual impact, but it detects a problem only after someone has experienced it.
We provide synthetic monitoring. A production run can reuse an adapted part of the regression scenarios, but requires dedicated accounts, controlled data and clean-up, as well as security rules for the particular integrations. RUM complements it well: a synthetic scenario verifies the agreed journey, while RUM describes the experience of actual visitors according to the available data.
What the right combination gives you
- You can detect an outage in a key journey within the configured interval and confirmation runs—even outside peak hours.
- You know whether a customer can complete a purchase, not merely whether the server responds.
- By adding RUM, you gain both proactive monitoring and a real-world view of performance.
Next step
Do you have analytics but no alert when checkout fails? During a no-obligation consultation, we will propose scenarios, an interval and alerting rules for your key journeys.