Synthetic Monitoring: Proactive Quality in Production
Synthetic monitoring uses scripted test transactions — "synthetic users" — to continuously verify that critical application functionality is working correctly in production. Unlike real user monitoring (which only detects failures after real users experience them), synthetic monitoring proactively executes critical user journeys on a schedule and alerts when they fail.
How Synthetic Monitoring Works
Synthetic tests are scripts that simulate real user interactions: navigate to the login page, enter credentials, verify successful login, navigate to a key feature, perform an action, verify the result. These scripts run from multiple geographic locations every few minutes. If any step fails, an alert fires immediately — typically before real users have noticed an issue.
What to Monitor Synthetically
- Authentication: login and logout for each auth method
- Core value actions: the key things users come to the product to do (checkout, creating a record, sending a message)
- Critical integrations: payment processing, email delivery, key API calls
- Performance: verify that critical pages load within acceptable time thresholds
Synthetic vs Real User Monitoring
Real user monitoring (RUM) measures actual user experience from real browser sessions — performance, errors, and interactions as they actually occur. Synthetic monitoring complements RUM: synthetics provide constant baseline checks; RUM provides insight into actual user experience diversity. Both are needed for comprehensive production quality visibility.
Tools
Checkly (developer-focused, uses Playwright), Datadog Synthetics, New Relic Synthetics, Pingdom (simpler), k6 Cloud (load + synthetic).