Comparing Real User Monitoring (RUM) vs. Synthetic Monitoring

Monitoring application and website performance has become critical to delivering a smooth digital experience to users. With users' attention spans dwindling at an ever-increasing rate, even minor hiccups in performance can cause users to abandon an app or website. This directly impacts key business metrics like customer conversions, engagement, and revenue.

To proactively identify and fix performance problems, modern DevOps teams rely heavily on monitoring solutions. Two of the most common techniques for monitoring website and application performance are Real User Monitoring (RUM) and Synthetic Monitoring. RUM focuses on gathering data from actual interactions, while Synthetic Monitoring simulates user journeys for testing.

This article provides an in-depth exploration of RUM and Synthetic Monitoring, including:

• How each methodology works
• The advantages and use cases
• Key differences between the two approaches
• When to use each technique
• How RUM and Synthetic Monitoring can work together

The Growing Importance of Performance Monitoring

Digital experiences have become the key customer touchpoints for most businesses today. Whether it is a mobile app, web application, or marketing website — the quality of the user experience directly impacts success.

However, with the growing complexity of modern web architectures, performance problems can easily slip in. Issues may arise from the app code, web server, network, APIs, databases, CDNs, and countless other sources. Without comprehensive monitoring, these problems remain invisible.

Performance issues severely impact both customer experiences and business outcomes:

• High latency leads to sluggish response times, hurting engagement
• Error spikes break journeys, increase abandonment
• Crashes or downtime block customers entirely

To avoid losing customers and revenue, DevOps teams are prioritizing user-centric performance monitoring across both production systems and lower environments. Approaches like Real User Monitoring and Synthetic Monitoring help uncover the real impact of performance on customers.

Real User Monitoring: Monitoring Actual User Experiences

Real User Monitoring (RUM) tracks the experiences of real-world users as they interact with a web or mobile application. It helps understand exactly how an app is performing for end users in the real world.

Source

Key Benefits of Real User Monitoring

Accurate Real-World Insights

• Visualize real user flows, behavior, and activity on the live site
• Segment visitors by location, browser, device type, etc.
• Analyze peak site usage periods and models.

RUM data reflects the true uncontrolled diversity of real user environments - the long tail beyond synthetic testing.

Uncovering UX Issues and Friction

• Pinpoint usability struggles leading to confusion among users
• Identify confusing page layouts or site navigability issues
• Optimize UX flows demonstrating excessive abandonment
• Improve form completion and conversion funnel success

Human insights expose true experience barriers and friction points.

User Behavior Analytics

Source

• Which site areas attract the most user attention and which the least?
• Diagnose ineffective page layouts driving away visitors
• Analyze visitor attributes for key personas and audience targeting
• Identify navigability barriers confusing users

Analytics empower understanding your audience and keeping them engaged.

Production Performance Monitoring

• Waterfall analysis of page load times and request metrics
• JavaScript error rates and front-end performance
• Endpoint response times and backend throughput
• Infrastructure capacity and memory utilization

RUM provides DevOps teams with visibility into how an application performs for genuine users across diverse environments and scenarios. However, RUM data can vary substantially depending on the user's device, browser, location, network, etc. It also relies on having enough real user sessions across various scenarios.

Synthetic Monitoring: Simulating User Journeys

Synthetic Monitoring provides an alternative approach to performance monitoring. Rather than passively gathering data from real users, it actively simulates scripted user journeys across the application.

Source

These scripts replicate critical business scenarios - such as user login, adding items to the cart, and checkout. Synthetic agents situated across the globe then crawl the application to mimic users executing these journeys. Detailed performance metrics are gathered for each step without needing real user traffic.

Key Benefits of Synthetic Monitoring

Proactive Issue Detection

• Identify performance regressions across code updates
• Find problems impacted by infrastructure changes
• Validate fixes and ensure resolutions stick
• Establish proactive alerts against issues

Continuous synthetic tests enable uncovering issues before users notice.

24/7 Testing Under Controlled Conditions

• Accurately test continuous integration/deployment pipelines
• Map performance across geography, network, and environments
• Scale tests across browsers, devices, and scenarios
• Support extensive regression testing suites

Synthetic scripts test sites around the clock across the software delivery lifecycle.

Flexible and Extensive Coverage

• Codify an extensive breadth of critical user journeys
• Stretch test edge cases and diverse environments
• Dynamically adjust test types, frequencies, and sampling
• Shift testing to lower environments to expand coverage

Scripting enables testing flexibility beyond normal usage.

Performance Benchmarking and Alerting

• Establish dynamic performance baselines
• Continuously validate performance SLAs
• Trigger alerts on user journey failures or regressions
• Enforce standards around availability, latency, and reliability

Proactive monitoring enables meeting critical performance SLAs.

By controlling variables like device profiles, browsers, geo locations, and network conditions, synthetic monitoring can test scenarios that may be infrequent from real users. However, synthetic data is still an approximation of the real user experience.

Key Differences Between RUM and Synthetic Monitoring

While RUM and synthetic monitoring have some superficial similarities in tracking website performance, they have fundamental differences:

In a nutshell:

• RUM provides real user perspectives but with variability across environments
• Synthetic monitoring offers controlled consistency but is still an estimate of user experience

When Should You Use RUM vs. Synthetic Monitoring?

RUM and synthetic monitoring are actually complementary approaches, each suited for specific use cases:

Use Cases for Real User Monitoring

• Gaining visibility into real-world analytics and behavior
• Monitoring live production website performance
• Analyzing user satisfaction and conversion funnels
• Debugging performance issues experienced by users
• Generating aggregated performance metrics across visits

Use Cases for Synthetic Monitoring

• Continuous testing across user scenarios
• Benchmarking website speed from multiple geographic regions
• Proactively testing staging/production changes without real users
• Validating performance SLAs are met for critical user journeys
• Alerting immediately if user flows fail or regress

Using RUM and Synthetic Monitoring Together

While Real User Monitoring (RUM) and Synthetic Monitoring take different approaches, they provide complementary visibility into application performance.

RUM passively gathers metrics on real user experiences. Synthetic proactively simulates journeys through scripted crawling. Using both together gives development teams the most accurate and comprehensive monitoring data.

Some key examples of synergistically leveraging both RUM and synthetic monitoring:

Conclusion

Real User Monitoring (RUM) and Synthetic Monitoring provide invaluable yet complementary approaches for monitoring website and application performance. RUM provides accuracy by gathering metrics on actual user sessions, exposing real points of friction. Synthetic provides consistency, testing sites around the clock via scripts that simulate user journeys at scale across locations and environments.

While RUM reveals issues currently impacting real users, synthetic enables proactively finding potential problems through extensive testing. Using both together gives organizations the best of both worlds — accurately reflecting the real voices of users while also comprehensively safeguarding performance standards. RUM informs on UX inefficiencies and conversion barriers directly from user perspectives, while synthetic flexibly tests at breadth and scale beyond normal traffic levels.

For preventative and end-to-end visibility across the technology delivery chain, leveraging both real user data and synthetic crawling provides the most robust web performance monitoring solution. RUM and synthetic testing offer indispensable and synergistic visibility for engineering teams striving to deliver seamless digital experiences.