Synthetic monitoring is the practice of running scripted, scheduled checks against a website from controlled probe locations — as opposed to real-user monitoring (RUM), which captures data from actual visitors. It catches issues even when traffic is low.
Synthetic checks range from simple HTTP GETs to full headless-browser scripts that log in, click through a checkout, and verify the order confirmation page. They run on fixed intervals (typically 1-5 minutes) from multiple regions and produce consistent, comparable data.
The trade-off versus RUM: synthetic is repeatable and catches issues even at 3am with no users online, but it doesn't reflect the diversity of real-user devices, networks, and behaviour patterns.
Synthetic monitoring is the only way to detect outages on low-traffic pages, validate uptime against SLAs (you control the measurement), and catch deployment regressions immediately rather than after users start complaining.
See it in the product: All features.