Visitor Monitoring The Functional Difference Between Synthetic and Real User Monitoring | Keynote

The Functional Difference Between Synthetic and Real User Monitoring

By Aaron Rudger | February 27, 2015

CATEGORIES: Web Performance

If your business depends on the performance of your website and/or apps, you should consider ordering monitoring services right now. There are two primary types—real user monitoring (aka RUM) and synthetic monitoring, and it is important to learn their intrinsic differences before making a decision. Both of them have pros and cons, but most experts suggest that businesses opt for a customized solution that incorporates a combination of both since they complement one another. Together, they will show you exactly how long your pages are taking to load for real users while providing the detailed analysis required to diagnose and improve performance. Both of these monitoring types can be utilized for web, mobile, and tablet browsers.

Synthetic Monitoring

Synthetic monitoring, often called active or proactive monitoring, simulates real user traffic utilizing a variety of external agents located in datacenters around the world that run scripted transactions against a web application.  These scripts mimic the behavior of a typical user such as running a search, viewing a product, logging in, and checking out—in other words, gathering data that simulates real user experience. In the past, synthetic monitoring was typically done using lightweight, low-level agents, but increasingly, it is necessary to run full web browsers to process JavaScript, CSS, and AJAX calls that occur on page loads.

Synthetic monitoring is more predictable than real user monitoring because the script executes a known set of steps at intervals from a known location. It is better for setting alerts and for assessing site availability and network problems, especially if it utilizes integrated network insight. With full client control, synthetic monitoring yields amazingly detailed waterfall charts, resource-by-resource performance, and screenshots/videos of page loads in action.


  • Consistent and stable baseline
  • Sensitive to small changes in performance
  • Nothing to install
  • Tests site availability even when usage is low or non-existant
  • Ability to measure and compare any website
  • Provides detailed assets analysis
  • Records the user experience via screenshot and (sometimes) video
  • Performance waterfall charts


  • Limited sample size and page reach
  • Limited geographic coverage
  • Difficult to maintain for fast-changing sites

Real User Monitoring

Most real user monitoring today utilizes JavaScript embedded in web pages to gather performance data about the end user’s perspective as they browse your website. This approach allows you to correlate web performance with user behavior by comparing actual user experience metrics to actions like conversion and engagement. You can monitor important transactions such as making a purchase, quoting an insurance policy, or requesting customer service and determine actual trends. Real user monitoring answers the following questions:

  • How many customers may be impacted by outages and performance issues detected by active “clean room” measurements?
  • What issues are impacting user behavior including conversion, abandonment, and engagement?
  • How is the entirety of my site performing beyond the home page and a few other transaction pages?


  • Large sample size
  • Real network and browser conditions
  • Limitless geography
  • Conversion and KPI correlation with performance metrics


  • Requires installation of JavaScript
  • Limited performance metrics
  • Limited ability to provide detailed assets analysis
  • Requires significant site usage to yield reliable results

Keynote’s integrated active and real user monitoring capabilities give you a complete and actionable solution for identifying issues and opportunities. Contact Keynote today to see how a customized solution can help you understand and improve user experience—after all, your customers are your greatest asset and deserve the best monitoring solution.

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