Uptime.com Blog

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

Three seconds is a very important number for website owners and developers that work on web applications. This is because they know 50% of visitors are likely to abandon a website if it takes longer than three seconds to load. With such a high risk of losing potential customers, website developers invest a lot of time and effort into optimizing and refining their website’s code to improve its speed and user experience.

However, while uptime monitoring can prevent downtime, it isn’t enough to ensure a positive user experience. A website may be technically up and running, but if it takes too long to load, visitors may still abandon the site before it completely renders. This is where monitoring tools like real user monitoring (RUM) and synthetic monitoring come in.

RUM and synthetic monitoring are two different methods of monitoring website performance, each with its own strengths and weaknesses. While both aim to improve website performance, they take different approaches to achieve this goal.

In this article, we’ll explore the differences between RUM and synthetic monitoring and help you understand why using both approaches is best if you want to optimize your website’s speed and overall user experience and ensure that your visitors stick around and convert into customers.

What Is Synthetic Monitoring?

If you are asking yourself what is Synthetic Monitoring, it is a popular method of active monitoring that will help determine that a website performs and is functional. By simulating user activity on a website or application, developers can test response times, performance, and functionality. Synthetic monitoring enables developers to identify performance issues before they impact users.

How Synthetic Monitoring Works

Instead of tracking real users on a site, synthetic monitoring uses a service to simulate user activity. These services can simulate an array of user activities, including page views, button clicks, and form submissions, and supply developers with data on response time and performance.

Developers often use synthetic monitoring to ensure that the performance changes they make to code actually achieve their intended goal. By comparing test results before and after changes, developers can determine if a page loads faster and verify that their changes have the desired effect. Synthetic tests should be run periodically so that current results can be compared to past results and issues can be found and fixed before they affect users.

Benefits and Limitations

One of the primary benefits of synthetic monitoring is that it enables developers to test performance and functionality across different devices, browsers, and networks. Synthetic monitoring allows developers to replicate real-world scenarios to test response times and performance. Additionally, synthetic monitoring usually uses fewer resources and is easier to implement than RUM.

However, one potential limitation of synthetic monitoring is that it cannot simulate the actions of real users or capture user experience issues they may have. Synthetic monitoring only tests predefined scenarios, which may not accurately represent actual user behavior. Additionally, synthetic monitoring may not be able to account for slow networks, which can impact real user experience.

What Is Real User Monitoring (RUM)?

Real User Monitoring (RUM), also known as end-user experience monitoring or digital experience monitoring, is a powerful method of passive monitoring that tracks user behavior and collects data on key metrics such as page load time, time to first byte (TTFB), and overall user experience. Unlike synthetic monitoring, RUM captures actual user data and provides developers with a performance monitoring tool that helps them determine how an application performs in the real world.

How RUM Works

One of the primary benefits of RUM is its ability to provide insights into user behaviors and activities, including the web pages they view, the elements they click, and how they interact with the website in general. This data can be used to find performance issues and optimize a website or application code to improve overall user experience.

Additionally, RUM allows developers to capture data on user behavior over time, determine how performance metrics have changed, and identify patterns affecting user experience. By analyzing this data, developers can quickly identify issues and prioritize improvements to optimize website responsiveness.

Benefits and Limitations

One of the main advantages of RUM is its capacity to collect information concerning a variety of user activities, such as page views, clicks, and user interactions with different website elements. RUM captures data on user behavior, allowing developers to find problems with performance and fix them for a consistent and positive user experience.

However, one potential limitation of RUM is that it can be more resource-intensive and complex to implement than synthetic monitoring. Because RUM requires collecting and analyzing user data, it may require additional infrastructure and resources to implement effectively. Additionally, RUM may not be suitable for all types of websites or apps, particularly those with low traffic volumes or short user sessions.

RUM Vs. Synthetic Monitoring: Pros and Cons

Both RUM and synthetic monitoring offer benefits and limitations depending on your website or application’s needs. Here is a breakdown of the key pros and cons of each method:

RUM Pros

• Provides an accurate picture of website or application performance by capturing data on actual user behavior
• Can capture insights on a large variety of user behaviors, allowing developers to identify performance issues and optimize the application for a better end-user experience
• Allows for the collection and analysis of user data over time, providing insights into trends that could be impacting user experience

RUM Cons

• Can be more resource-heavy and complicated to implement than synthetic monitoring
• May not work well with websites or applications that do not have much traffic or user activity
• May not be able to identify performance issues caused by network latency or other factors outside of the website or application

Synthetic Monitoring Pros

• Can simulate a broad range of user behaviors, enabling developers to examine response times and performance across a selection of devices, browsers, and networks
• Typically less resource-intensive and easier to implement than RUM
• Can find performance problems before they impact users

Synthetic Monitoring Cons

• Cannot replicate real user behavior or identify user experience issues
• May not represent actual user behavior accurately or account for variables such as network latency that can impact real user experience
• Only tests predefined scenarios and may not catch unexpected or new issues

Real User Monitoring Vs. Synthetic Monitoring: Which is Better for Your Website?

When it comes to website monitoring, both real user monitoring (RUM) and synthetic monitoring have advantages and disadvantages. Here are some factors to consider when choosing the type of monitoring you should use to find the insights you are looking for.

Real-Time User Feedback

One of the major advantages of RUM is that it provides real-time feedback from actual users. By tracking user behavior, RUM allows you to find issues and make improvements for a better user experience. However, it can be difficult to isolate the cause of a problem when it’s tied to a specific user or set of users.

Controlled Environment Testing

Synthetic monitoring provides a controlled environment to test website performance. By running predefined scripts against your website, synthetic monitoring can simulate user behavior and provide detailed data on response times and service availability. This helps you find issues before they impact real users. However, synthetic monitoring doesn’t capture the nuances of real user behavior and may not detect all issues.

Benchmarking Performance

Synthetic monitoring is particularly useful for benchmarking performance against competitors and industry standards. By running tests from different locations around the world, synthetic monitoring can provide detailed metrics on responses and availability. This allows you to identify areas where your website may be falling behind and make improvements to gain a competitive edge.

Accuracy and Reliability

Both RUM and synthetic monitoring have their strengths and weaknesses when it comes to accuracy and reliability. RUM provides real user data, which can be more accurate but may be impacted by outliers and other factors.

Synthetic monitoring provides controlled testing environments, which can be more reliable but may not always reflect real user experiences. Understanding the accuracy and reliability of your monitoring solution is important for making informed decisions and identifying issues on your website.

Data Visualization and Reporting

Both RUM and synthetic monitoring generate a large amount of data, but how they are visualized and reported can differ. RUM typically provides real-time dashboards and visualizations, while synthetic monitoring generates reports and alerts based on predefined thresholds. The type of data visualization and reporting that works best for your needs will depend on your specific needs and use cases.

RUM and Synthetic Monitoring: Better Together

RUM and synthetic monitoring both have their wheelhouses, but that doesn’t mean you have to choose one or the other for your monitoring strategy. There are places where using them together will provide even more insights. Here are some ways these two approaches can complement each other:

Correlating Performance with Business Metrics

Synthetic monitoring can help identify performance issues, such as network bottlenecks and slow page load times. However, to understand how web performance affects business revenue, you need more than just synthetic performance data.

RUM data can provide insights into metrics that matter to the business because it provides insights into how real users are experiencing a website, which can then be correlated with the continuous performance metrics collected from synthetic testing.

Early Identification of Application Issues

It is common for infrastructure maintenance to occur during off-peak hours, which can cause unforeseen application problems. Synthetic monitoring can identify configuration problems caused by maintenance changes before active users arrive in the early morning hours. In contrast, RUM is most helpful in measuring web application responsiveness during peak hours for each and every live user.

Testing in Staging Environments

RUM data is generated through real user traffic, making it difficult to evaluate the performance of new features in development, testing, or staging environments. On the other hand, synthetic monitoring allows you to determine how these new features will affect the application before they are released to production.

By combining RUM data with synthetic monitoring, you can create realistic use cases that better match what is happening in your production environment and use them to create more thorough synthetic transaction monitoring.

Troubleshooting Performance Issues

Using both synthetic and RUM data to troubleshoot performance problems can make finding them quicker and easier. When a synthetic test fails or sends an alert, you can use the data from RUM to determine if the error is currently impacting the experience of end users.

On the other hand, if your RUM reporting shows a performance issue, you can create synthetic transaction checks to simulate the same user journey from various ISPs and geographical locations. By using the data from both synthetic monitoring and RUM, you can narrow down the root cause of the problem and discover a solution for it quicker than using just one monitoring tool.

End-to-End Website Visibility

By using both RUM and synthetic monitoring, you can achieve end-to-end visibility into your website’s performance. RUM provides feedback from actual users, allowing you to understand how they interact with your website and identify issues that impact their experience. Synthetic monitoring provides a baseline for website performance, allowing you to find problems and make improvements in a controlled environment. Together, these two methods provide a complete view of website performance.

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.

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