To start, if you're new to synthetic monitoring, I recommend exploring this synthetic monitoring overview. In today's fast-paced world of web development, browser synthetic testing is a vital tool in the observability toolbox. With technical debt piling up faster than code reviews, it's essential to have a strategy in place that gives you confidence in your application's health. As someone who’s been responsible for delivering high-quality, high-confidence observability services across several Fortune 500 companies, I can confidently say: I slept better knowing our critical client-facing applications had synthetic monitoring coverage.  Synthetic monitoring isn’t just a buzzword; it’s an active safety net that ensures your site’s availability, performance, and functionality are up to par, even when no one’s watching. When your synthetic browser monitoring spots a problem, especially on mission-critical apps, you know it’s a real problem that needs to get fixed fast. As an observability practitioner, I've spent countless hours in the trenches, implementing & tuning synthetic browser monitoring to catch potential issues early. These tools work in harmony with passive monitoring approaches like RUM and APM. Over time, I’ve gathered insights and best practices that I’d like to share with you—especially if you’re looking to fine-tune your synthetic browser tests for success. 1. Power in Simplicity   Enterprise web applications are stuffed with features, but not all of them are equally important. For an e-commerce site, the critical functions include the landing page, login, product search, and payment. While features like live chat, profile customization, and social sharing are cool, they won’t break the business if they’re down for a while. Draft a Short User Journey Start by working with someone who knows the ins and outs of the app—maybe the end-user or product manager. Together, map out the user journey they typically take, noting prerequisites (like login before checkout) and success criteria (e.g., seeing “Welcome, John Doe” after logging in).  If possible, record this session to reference while building your synthetic tests. You’ll also want to group certain steps into transactions—this helps you logically organize the journey, generate transactional KPI’s, and focus on key points in the flow. Using transactions lets you focus on the relevant things the user does, not the minutiae of what page was loaded when. Focus on Critical Actions When designing your tests, stay focused. It’s tempting to test everything, but remember: just because you can doesn’t mean you should. Stick to the critical actions you identified earlier, like logging in, searching, and making purchases.  Finally, focus on underlying service invocation —you want your synthetic tests to complement passive monitoring strategies like APM, not replace functional testing. Ideally, your synthetic testing will also exercise key backend components. You’d do this by making sure to build user workflows that reflect all the critical functionality your site has to offer. As a bonus, in Splunk Synthetic Monitoring, you can even see directly how user transactions affect your backend services from each synthetics run. 2. Validate User Actions A synthetic test is only as good as its validation. Ensuring each user action produces the expected result is critical. Confirm Actions Have the Intended Result Leverage assertions to validate that content renders correctly. For instance, testing a search function at Splunk T-shirt co? Instead of searching for “Supernova limited Edition T-Shirt,” invoke a search for “shirt”. In this example, when the limited edition shirt is no longer available the test would fail and need to be updated, however it utilizing the search term “shirt” would always return results.  Build Robust Tests to Avoid False Positives False positives are the bane of synthetic tests. A robust strategy can minimize them, such as using fuzzy searches instead of exact terms, like mentioned above. You can also implement assertions to wait for elements to load before interacting with them, preventing a race condition from failing your test. Also, be mindful of things like maintenance/downtime windows, as tests run during these times may result in false positives. And, of course, test in the same environment configuration that your users will experience—this includes matching viewport size, cookies, and browser settings. 3. Test Hygiene Matters Keeping your tests organized is just as important as the tests themselves. Follow a Naming Convention A consistent naming convention makes it easier to manage your tests. Use names that clearly reflect the application, environment, or action being tested. For instance: `Application XYZ Checkout_Success_Prod_Test`. Add Custom Properties (Tags) Tagging tests with custom properties—like `app_name`, `environment` , support_level, or `component`—helps with test isolation and troubleshooting. You can use these tags to quickly filter your tests in order to isolate issues or you might leverage them in your alerts to provide additional context to responders. Align these tags with your organization's existing tagging standards for maximum clarity. Use Consistent Testing Locations Ensure your tests are run from consistent locations to get reliable, comparable results. Make sure those locations are aligned with your users’ geography—whether internal or external. Leverage variables  Many robust Synthetic monitoring solutions provide a means to variablize parameters utilized in your test configuration. Leveraging variables allows for centralized management of variables. A common use case would be to store a regularly leveraged username and password in variables. In this example, if you need to update the username or password, you now simply update the variables instead of searching through your synthetics test configuration and updating the tests one-by-one.     4. Act! Alert! Alert! Once your tests are in place, you need a reliable alerting strategy. High-confidence alerting is crucial to respond quickly when an issue arises. The biggest advantage of synthetic monitoring is the knowledge that a failure is generally highly-actionable (assuming you’ve followed the rules earlier in this article to generate good tests.) Build Detectors for KPI Thresholds Set up detectors to alert on KPI thresholds, such as availability and performance. For example: Start by monitoring on page availability, server errors (HTTP status codes > 500), or deviations of the KPI for your synthetic browser test transactions (I.E. search is slow to return results).  Start Simple with Availability Alerts Begin with basic availability alerts to ensure your site is online. Some common availability alerts include checks for SSL certificate validity and server connection errors (status codes > 500). Once your tests are stable, evolve your alerting thresholds to react to seasonal or historical anomalies for critical performance metrics, rather than relying on static thresholds. A great place to start with performance alerts is at the transaction level, for example, generating alerts if the time it takes to render search results or authenticate a user deviates from the historic baseline.  And remember: document everything! Knowing what your test does and why will help your team respond appropriately when alerts trigger. Analyze and Optimize Synthetic browser tests are capable of generating vast amounts of data. Common synthetics metrics include page performance timings, page web vitals (CLS, LCP, TBT), page Connection timings, page resource and error counts, score metrics (such as Lighthouse), page content size metrics, and transaction-level metrics (duration, requests, & total size) This data can be extremely valuable for troubleshooting failures and/or identifying optimization opportunities . For example:  Regularly review your Core Web Vitals and determine if they differ from industry standards. Implement optimizations/improvements and leverage the data to determine the effect. Integrate your deployment pipelines with your synthetic testing data. This will allow you to overlay application deployments and quickly correlate changes with availability issues and/or deviations to performance metrics. Develop common synthetics test dashboards that help analyze your synthetic data over time. Reference these dashboards in your alerts, as this analysis should expedite the response process and ultimately reduce MTTR.   Conclusion Synthetic browser tests are an invaluable part of the modern observability stack, but only if you approach them with care and strategy. Keep your focus on critical user journeys, validate thoroughly, maintain solid test hygiene, and always stay alert (literally). By applying these tips, you’ll not only enhance your synthetic testing framework but also provide more robust observability coverage for your applications. If you’re interested in content similar to this, I’d encourage you to check out the Observability Developer Evangelist blogs and/or our YouTube Playlist.    ... View more