rum vs synthetic monitoring

Real User Monitoring (RUM) vs Synthetic Monitoring: What Are the Differences?

Three seconds is a very important number for website owners. They know that 50% of visitors will leave their website if it doesn’t load in that time. Website developers spend a lot of time optimizing and refactoring code so that it runs more quickly and provides a better user experience.

User experience is something that monitoring only uptime won’t tell you. A website might be up, but if it takes 10 seconds to load, customers will bounce. This is where RUM and synthetic monitoring come in. They are both methods of monitoring website performance, but they go about it in different ways.

What Is Synthetic Monitoring?

Synthetic monitoring is a method of actively monitoring a service to determine if it is working and performing well. Instead of tracking real users on a site, it uses another service that simulates user activity to test response time and performance.

Developers often use synthetic monitoring to ensure that the performance changes they make to code actually do what they were supposed to do. They can compare the results of tests before and after a change to determine if a page loads faster. It is also good to run synthetic tests periodically, so current results can be compared to past results and issues are found and fixed before they reach customers.

What Is RUM?

Real user monitoring – also known as digital experience monitoring or simply user monitoring – is monitoring that records the experience of actual users of a website and will provide insights into how they are interacting with it. It functions similarly to web analytics software.

Real user monitoring allows website owners to dig deep into website performance metrics.  The generated report aggregates and visualizes the data to help spot problems and anomalies. This type of passive monitoring will help you find the irregularities where user experience is poor—for example, when users from a specific geographic location are having issues with performance.

RUM vs Synthetic Monitoring

Due to the differences between these two types of monitoring, each has its pros and cons.

The pros of synthetic monitoring include:

  • Tests can run at any time and on any workflow because it doesn’t require real users
  • Tests can be used as a benchmark against competitors to compare your site to theirs or to compare the current performance of a site to past performance
  • Bugs and performance issues can be caught before users see them

The cons of synthetic monitoring include:

  • Because the tests are not based on real users, admins may not see the UX or UI issues real users are experiencing
  • The tests are very predictable when user interactions are not
  • It can only answer questions that you have when you set up the tests

The pros of RUM include:

  • It puts users first by using their actual experiences as a guide for what needs to be fixed
  • It captures every possible data point on user experience if it is set up to do it
  • It will find issues both at the network level and the page level

The cons of RUM are:

  • It requires real traffic to a website in order to work
  • It lacks the ability to benchmark performance
  • It can store a lot of data

Why Choose If You Don’t Have To?

Both RUM and synthetic monitoring are valuable methods of determining the performance of a resource, and it isn’t an either/or choice. They are best used together. Synthetic monitoring can help you monitor new features that don’t yet get traffic, diagnose short-term issues with performance, and establish a performance baseline, while RUM will help you to identify and monitor long-term performance trends.

Ready to set up real user and synthetic monitoring? You can start for free with our 14-day trial.

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Stephan is a senior software engineer and has been a developer for almost two decades. Some topics he’s covered include network security, web development, web analytics, artificial intelligence, 3D modeling, and programming in PHP, Python and JavaScript.

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