Website monitoring solutions play a significant role in maintaining the performance, availability, and reliability of the digital world. The insight provided by monitoring tools is helping online applications improve while delivering a positive end-user experience. Performance of an application has a direct impact on factors that define a successful business, such as:

  • Customer satisfaction
  • Online traffic and bounce rates
  • Conversions rates
  • Business revenue

An ideal monitoring strategy allows you to understand precisely where to improve the application and how well the application performs compared to competitors. Most monitoring solutions provide either passive or active monitoring. Real user monitoring (RUM) is passive while synthetic monitoring is an active monitoring type. In this blog, we discuss how these differ and how most the robust monitoring strategy includes both RUM and Synthetic.

Real user monitoring (RUM)

Real user monitoring falls into the passive monitoring category. It tracks performance data from real users accessing the application. The performance data from RUM is diverse since the data is collected directly from the end user. And the end user could be using a combination of any browser, any ISP or any device. So, the data reflects the “real” end user experience.

RUM is implemented by adding Javascript tags to the application code. The script triggers when a user accesses the application, and it gathers data for different performance metrics. This data is relayed back to the RUM platform which allows you to analyze performance and understand user behavior.

Synthetic monitoring

On the other side of the monitoring spectrum is synthetic monitoring. This is an active monitoring method that collects performance data using agents simulating real end user behavior. Synthetic monitoring works in a pre-configured environment, and the tests are set up to use a specific browser, device or network.

Synthetic monitoring does not require embedding code snippets in the application so it can be used to analyze the performance of competitors and to benchmark the major players in the industry. These tests can replicate multiple user journeys which can identify potential performance issues before it impacts the end user.

Real user monitoring vs synthetic monitoring

RUM and synthetic are very different in the way it is integrated and how it works but both help keep track of application performance. Both provide valuable insight into user behavior, network latency or bottlenecks, performance trends, and overall health of the application.

When evaluating these two monitoring types you should first look at the value each adds to your monitoring strategy.

Synthetic monitoring you can:

  • Simulate user journey in a controlled environment
  • Run tests at scheduled intervals to proactively capture potential issues
  • Build tests based on key business transactions

Synthetic monitoring helps you:

  • Reduce MTTR (Mean Time to Resolve) as the tests actively track application performance
  • Get alerts whenever there is a notable variation in any performance metric, including downtime.
  • Monitor performance in a pre-production environment
  • Benchmark competitors
  • Track service level agreement (SLA) breaches
  • Monitor performance of third-party services

RUM monitoring you can:

  • Gather data from real end users across a variety of environments
  • Collect diverse data for every user accessing the application
  • Configure variables to track and collect specific data

RUM monitoring helps you:

  • Capture real end-user experiences from different devices, browsers, geo-location, etc.
  • Correlate user engagement and business KPIs with application performance
  • Utilize historical data to predict performance trends and business outcomes

What type of monitoring do you need?

RUM and Synthetic aim to improve application performance by giving you insight into every process in the application delivery chain. A choice of real user monitoring vs synthetic monitoring will not result in an ideal strategy. Synthetic and RUM complement each other. A comprehensive monitoring solution should include both types of monitoring to get a 360-degree view of your application.

The examples below illustrate how RUM and Synthetic complement each other.

Correlating business with performance

Synthetic monitoring can provide the performance data you need to analyze end user experience. For example, how fast did the page load? Is there latency in the network? What is causing the latency? But, if you want to analyze exactly how the performance impacts your business revenue, then you need more than just synthetic performance metrics. RUM provides insight into the business metrics such as conversion rates which can then be used to correlate with performance metrics.

Testing applications in a staging environment

Since RUM collects data when an actual user accesses the application, it is not possible to gauge the performance of new features in a pre-production environment. In such a scenario, synthetic monitoring allows you to test the impact of changes to the application before the changes go live. The RUM data is an added advantage here as it provides real use cases that can then be simulated using synthetic monitoring for detailed testing in a staging environment.

Troubleshooting outages

Combining Synthetic and RUM data can make troubleshooting quicker and easier. When Synthetic tests fail or triggers an alert, the RUM data will show you the real time impact on end-user experience. Similarly, if RUM data reveals a performance anomaly then you can use Synthetic to replicate the issue across a number of ISPs and geographies. The data can be sliced and diced to identify the root cause. RUM and Synthetic can be used simultaneously to verify performance issues and it aids in advanced troubleshooting.


RUM and synthetic provide insight into how well your application performs. Although using one or the other will help analyze performance, combining synthetic monitoring with RUM results in a more robust and comprehensive monitoring strategy.

Read more about RUM and the Catchpoint RUM platform in our ebook and handbook.