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What Is Synthetic Monitoring?

Synthetic monitoring is a web performance monitoring technique that uses behavioral scripts to simulate end-user interactions with a website or application. The goal of synthetic monitoring is to understand how a real user might experience an app or website. This type of monitoring is done by directing a robot client on a predefined course through the app, simulating transactions to mimic what an end user might do. As the client proceeds through a typical user clickstream, performance metrics on the end-user experience are collected, analyzed and interpreted.

Synthetic monitoring can be used to collect a range of performance information and answer questions like:

  • “Is my website up?”
  • “How fast is my site loading?”
  • “Are shopping cart transactions working?”
  • “Is there any part of my transaction flow I can optimize?”

Synthetic monitoring checks are performed at regular intervals, and the frequency of these checks is typically determined by what is being checked. Availability, for example, might be checked once every minute.

Synthetic monitoring is an important tool for ensuring that an organization’s apps or services are available and responsive. In the following sections, we’ll look at how synthetic monitoring helps optimize website performance, how it works and some of the tools to look for.

What Is Synthetic Monitoring | Contents

The Basics of Synthetic Monitoring

Why is synthetic monitoring vital for end-user experience?

Synthetic monitoring is essential for optimizing website and web application performance. If your website performs sluggishly or returns frequent errors, your customers will abandon purchases or stop using the site altogether. Oftentimes, organizations aren’t aware their website performance lags behind competitors, and may not be able to resolve known issues quickly because of troubleshooting difficulties and overextended teams.

Synthetic monitoring keeps you on top of application performance. It provides a monitoring system that lets you know if your website is available, how fast it’s responding, and if business transactions are functioning in the expected manner. Over time, synthetic monitoring can help you establish performance benchmarks for modern applications and identify areas for improvement and optimization. Synthetic monitoring can also help you identify the source of potential slowdowns and failures with notifications so you can fix them before they impact your end users. In all, synthetic monitoring helps you ensure your organization consistently meets and raises the bar for your customer’s digital experience.

How does synthetic monitoring work?

Synthetic monitoring helps optimize website performance by simulating an actual user’s interaction with your website and associated services to help detect and resolve potential performance issues. It does this by monitoring three areas:

  • Availability: Synthetic monitoring can help you confirm website availability and its responsiveness overall. It can also make more granular assessments such as making sure specific content is available or that a specific API endpoint is available and responding as expected.
  • Web performance: Synthetic monitoring looks at web metrics such as page load speed, DNS time and Time to First Byte, as well as the performance of specific web page elements. It can alert teams to sluggish response times, errors and web content issues.
  • Transactions: Synthetic monitoring also provides transaction monitoring by evaluating the ability to complete specific transactions such as logins, clicks, form filling and checkout.
Availability, web performance and transactions are the three areas monitored through synthetic monitoring.

Synthetic monitoring optimizes web performance by monitoring three key areas.

Benefits and Challenges

What are the benefits of synthetic monitoring?

Synthetic monitoring offers many benefits. It enables you to:

  • Identify issues before they impact users: Synthetic monitoring tracks the performance of your website, APIs, SaaS applications, and more during both high- and low-traffic periods, and it alerts teams to availability issues and performance degradation. This puts you in a position to proactively find the root cause of problems with active monitoring and fix them before they negatively affect end users.
  • Measure Service Level Agreements (SLAs): Synthetic monitoring enables website monitoring of any third-party application at desired intervals from any location at any time. This can help you ensure service quality, identify problems more quickly, safeguard customer experiences and report on the compliance of internal or external providers.
  • Understand complex transactions and processes: Uptime and availability are not the only indicators of high-quality website and application performance. Synthetic monitoring enables you to emulate and conduct proactive monitoring of complex and critical processes such as form filling, logging in, adding items to a shopping cart, user transactions and checking out. The data gathered from these performance tests can then be compared among different geographical locations to baseline user interactions and identify potential improvements.
  • Test scaling capability: Synthetic monitoring lets you simulate high-traffic situations to check how your server will react under load, helping you make improvements to ensure your site can respond to expected or sudden traffic spikes.
  • Test new features: Synthetic monitoring allows you conduct experience monitoring to test new features before they go live to verify they operate as expected, see how they respond under load and if any of the changes impact third-party APIs.
  • Reduce MTTR: Synthetic monitoring is an effective tool for keeping MTTR low because it enables you to proactively identify and resolve issues before they affect the user.

What are the challenges of synthetic monitoring?

Although it offers many benefits, synthetic monitoring also poses a few challenges.

  • Complexity: Modern websites and applications are complex. They allow users to interact with them from a variety of geographies, devices and contexts. If not properly thought out in advance, it can be difficult for synthetic testing to account for all the possible performance situations that may occur.
  • Fragility: Synthetic tests can be fragile. If tests aren’t set up correctly, small UI changes, such as moving a button can cause scripted tests to fail, resulting in a storm of alert noise.
  • Limited precision: Not every path customers could take through your site or app can be tested — or even predicted in some cases. This means synthetic monitoring doesn't capture every possible customer use case. Because of this, synthetic monitoring is often used to monitor apps and websites in pre-production to find problems and establish baseline performance before they go live.

Getting Started

What are important synthetic monitoring tools?

An effective synthetic monitoring solution will provide complete visibility into your website and applications around the clock. When considering options, look for those that include a range of synthetic monitoring tools, such as:

  • Browser monitors: A real browser monitor simulates a user’s experience of visiting your website using a modern web browser such as Google Chrome. A browser monitor can be run at frequent intervals from multiple locations and alert you when your site or application becomes unavailable or when performance degrades below the baseline.
  • Click path monitors: Click path monitors also simulate a user’s visit to your site but monitor specific workflows. They allow you to create a custom script that navigates your website, monitoring a specific sequence of clicks and user actions, and which can be run at regular intervals.
  • Broken links monitors: These monitors allow you to create scripts that will test all the links for a specific URL. All failures are reported so you can investigate the individual unsuccessful links.
  • HTTP monitors: HTTP monitors send HTTP requests to determine the availability of specific API endpoints or resources. They should allow you to set performance thresholds and be alerted when performance dips below the baseline.
This graphic reiterated the four points made above when considering synthetic monitoring options.

Look for these tools when considering a synthetic monitoring solution.

How do you perform competitive benchmarking with synthetic monitoring?

Many synthetic monitoring tools include competitive benchmarking capability. This is one of the advantages of synthetic monitoring over real-user monitoring. With the latter, you need to put a JavaScript tag on the site or a software agent on the backend infrastructure that you want to monitor. It isn't possible to do this on a competitor’s website. With a synthetic monitoring tool, you typically need only provide the URL for a competitor’s website and you can monitor its performance just as would your own site. With the performance and user experience data you collect from a competitor’s site, you can essentially compare that data to your website’s to see how it stacks up.

Core Web Vitals and Synthetic Monitoring

What are Core Web Vitals (CWV)?

Core Web Vitals (CWV) are a set of metrics Google has established as important for a web page's user experience. They measure website performance factors in three key areas: load time, responsiveness and interactivity. CWVs are weighted in Google’s “page experience” score, which assesses a web page’s overall user experience.

CWVs track a variety of metrics to ensure the optimum user experience of your site and applications. Some of the most important include:

  • Response time: It’s essential to track the time it takes for a response to be sent from the server back to the client. You should also track DNS time, connection time and Time to First Byte. Any readings that are lower than baseline may indicate sluggish performance caused by limited bandwidth or server issues.
  • Input latency: Input latency measures the time between when a user makes a request — by clicking a link, tapping a button, etc. — to when that request is received and processed. The lower the latency, the better it is for the user experience.
  • Page load time: Monitoring CSS, scripts, DOM (Document Object Model) elements and third-party components is important for tracking overall page load time. Slow performance may indicate that large files, such as background images or videos, are the culprit.

Why are Core Web Vitals important for search engine position and organic visitors?

CWVs are important for search engine position and organic visitors because page experience is a Google ranking factor. Simply put, pages that provide great user experiences rank higher in Google searches than pages that deliver bad user experiences. While CWVs alone don’t tell the whole story about page experience — Google weighs them with other page-experience search factors such as HTTPS, mobile-friendliness, and a lack of interstitial pop-ups — they are a critical component of a holistic page-experience picture.

What are Google’s primary Core Web Vitals metrics?

Google includes three primary metrics in its Core Web Vitals metrics:

  • Largest Contentful Paint (LCP): Largest Contentful Paint measures how long it takes a web page to render the largest content blocks visible to the user from the time the user requests the URL. These elements include images, video poster (preview) images, background images and block-level text. Understanding how quickly these content blocks load is important because they signal to the user that the web page is loading. Load time is a critical factor in a positive user experience. Fast load times improve engagement and conversion rates, while sluggish load times can drive the user to abandon the page. Fast-loading pages are also more likely to rank higher in Google searches. LCP can help website owners determine if users will interact with a page and find it useful. According to Google, website owners should aim for an LCP of 2.5 seconds or less.
  • Cumulative Layout Shift (CLS): Cumulative Layout Shift measures how much a page layout shifts after the page has loaded. It’s an indication of the level of difficulty a user will have interacting with the page once it renders. If banners, buttons and links shift from when the page is loading to when it's fully rendered, it makes it more challenging for users to engage with these page elements. Similarly, a user can become frustrated if a web page’s text moves around while they’re reading the content. CLS helps site owners understand and improve the usability of their site by rating page layout shift with a score from 0 to 1, where zero means no shifting, and 1 indicates a high degree of shifting. Google suggests site owners maintain a CLS of 0.1 or less.
  • First Input Delay (FID): First Input Delay measures the time between a user’s first input — a clicked link or tapped button, for example — and when that page element responds. The measurement is taken from whichever element the user interacts with first. FID is important because modern websites utilize a variety of dynamic page elements that enhance user experience and improve content delivery but which can also cause delays when a user interacts with the page. Measuring input latency helps website owners understand how to optimize web pages to reduce the time users wait for a browser to respond to their input. Website owners should aim for a FID below 100 milliseconds, according to Google.

By monitoring Core Web Vitals in concert with other performance metrics, a synthetic monitoring solution can help you benchmark and improve website performance for your users across their entire journey.

The Future of Synthetic Monitoring

How does synthetic monitoring relate to observability?

As IT systems have become more complex with the incorporation of microservices, serverless and container technologies, conventional agent-based monitoring techniques and tools are becoming more limited in the level of visibility they can offer. They struggle with the high number of interdependencies and communication paths in these distributed architectures.

To overcome these challenges, performance monitoring will have a greater reliance on observability in the future. Observability is a measure of how you understand the internal states of a system based on knowledge of its external outputs. It leverages monitoring data and insights to provide a deeper, more holistic visibility into modern IT systems and their health and performance.

What is the difference between monitoring and observability?

The critical difference between monitoring, including synthetic monitoring, and observability is that monitoring demands that you know what’s important to monitor in advance. That’s limiting because it’s not possible to predict every potential error and failure in a modern distributed system. Observability, on the other hand, lets you decide what’s important to monitor by watching how the system performs over time and asking relevant questions about it as issues arise, such as “What is causing latency right now?” or “Is this issue impacting all mobile users right now or just some of them?” This more exploratory ability will become increasingly important as IT systems continue to evolve in complexity.

The Bottom Line: Synthetic monitoring is the key to unlocking a better user experience

Lagging response times, broken links and performance issues such as outages and downtime, can drive users away from your site or application — permanently, if they occur too often. Synthetic monitoring can help you get in front of performance problems before they impact your customers. An effective synthetic monitoring solution can help you keep your website performing at its best and ensure your users have the best possible customer experience.

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