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Synthetic monitoring probes your services from external locations on a schedule. Real user monitoring (RUM) captures actual user experiences in the browser or app. Most production systems benefit from both.

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Synthetic monitoring

Synthetic monitors send automated requests to your endpoints at regular intervals, regardless of whether real users are active. Strengths:
  • Detects outages 24/7, even during low-traffic periods
  • Consistent baseline — same check from the same location every time
  • Tests specific endpoints, assertions, and SLA compliance
  • Works before launch (no real traffic needed)
Limitations:
  • Tests a single path from a fixed set of locations
  • Doesn’t capture real user device/browser/network variation
  • Can’t measure client-side rendering performance

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What it looks like

Every 60 seconds:
  Probe (us-east) → GET /health → 200 OK (142ms) ✓
  Probe (eu-west) → GET /health → 200 OK (287ms) ✓

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Real user monitoring (RUM)

RUM embeds a script in your frontend that captures performance data from actual browser sessions. Strengths:
  • Reflects real user experience (device, browser, network)
  • Captures client-side metrics (LCP, FID, CLS)
  • Shows geographic and device-type distribution
  • Identifies performance issues that synthetic tests miss
Limitations:
  • No data during low-traffic periods
  • Higher noise (slow user networks, old devices)
  • Requires frontend instrumentation
  • Privacy and consent considerations

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When to use each

ScenarioRecommended
Detecting server-side outagesSynthetic
Monitoring APIs and background servicesSynthetic
Measuring real page load performanceRUM
Verifying SLA complianceSynthetic
Debugging performance by geographyRUM
Pre-launch testingSynthetic
Understanding actual user impactRUM

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Complementary, not competing

The most effective monitoring strategy uses both:
  1. Synthetic monitors as the reliability backbone — always running, always checking, providing the uptime SLA
  2. RUM for user experience insights — understanding what real users actually experience
When a synthetic monitor fires an alert, RUM data helps you understand the user impact. When RUM shows degradation, synthetic monitors help you isolate whether it’s your infrastructure or the user’s network.

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DevHelm’s approach

DevHelm focuses on synthetic monitoring — automated checks from distributed probe locations. This gives you reliable uptime data, response time tracking, and instant incident detection.

Multi-region monitoring

Run checks from multiple locations.

Response time budgets

Track and alert on latency thresholds.