When To Use Synthetic Monitoring vs. Real User Monitoring

Published: Friday, October 24, 2025 at 1:00 pm

Synthetic vs. Real User Monitoring: Choosing the Right Approach

Web teams face a crucial decision when it comes to monitoring website performance: choosing between synthetic monitoring and real user monitoring (RUM). Synthetic monitoring, often the starting point, uses simulated tests to assess how a site *should* perform under controlled conditions. However, it can fall short in capturing the complexities of real-world user experiences.

RUM, on the other hand, provides insights into how a website *actually* performs across various devices, networks, and geographies. It reveals issues that synthetic tests might miss, such as slow mobile performance or inconsistencies across different browsers.

The key lies in understanding when to use each approach. Synthetic monitoring excels when launching new features or pages. It allows teams to benchmark performance and catch regressions before deployment. However, once a feature is live, RUM becomes essential to monitor real user sessions and identify issues caused by third-party scripts, ad networks, or suboptimal networks.

RUM is also crucial for addressing regional or device-specific complaints. Synthetic monitors often run from limited locations, failing to predict issues faced by users on specific devices or networks. RUM provides data on the distribution of devices, browsers, and networks, enabling teams to understand how these factors impact user experience.

While synthetic monitoring is ideal for tracking availability and uptime, RUM provides context on the impact of incidents. It reveals who was affected and how severely, helping teams reproduce and resolve issues.

For optimizing Core Web Vitals and user experience, RUM offers valuable insights. It captures how metrics like Largest Contentful Paint (LCP) and Interaction to Next Paint (INP) behave across different conditions, providing a more accurate picture than synthetic tests.

Finally, when investigating backend or API slowdowns, both approaches are beneficial. Synthetic tests can confirm API performance, while RUM, with modern distributed tracing, can connect backend problems to real user experiences.

BNN's Perspective:

The choice between synthetic and real user monitoring isn't an either/or proposition. Both tools offer unique advantages. By combining synthetic monitoring for controlled testing and uptime checks with RUM for real-world insights, web teams can gain a comprehensive understanding of their website's performance and deliver a better user experience.

Keywords: synthetic monitoring, real user monitoring, RUM, website performance, Core Web Vitals, uptime, user experience, backend performance, API slowdowns, web development

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