Observability

Client-Side Telemetry That Proves Uptime

Capture user-side errors and latency to complement synthetics and logs.

By Alex KimHead of Reliability|Published December 23, 2025|7 min read
Dashboard with charts showing observability signals

Collect the right signals

Capture client errors, resource load times, and API failures with user impact context: device, network type, geo, and journey stage. Without this, you can't tell if a spike is real or a handful of poor connections.

Sample intelligently to cover key journeys without flooding storage. Keep 100% of checkouts and login flows, but downsample lower-value pages.

Normalize error names and URLs so you can correlate RUM with backend traces and synthetics quickly.

If customers see errors the backend missed, your uptime story is incomplete.

Correlate with synthetics

Compare RUM data to Watch.Dog synthetics to spot gaps or regional issues. If synthetics are green but users hurt, you're likely facing third-party script issues or CDN edges misbehaving.

Alert when client-side errors spike without matching server errors. That signal usually points to front-end deploys, ad/tag slowdowns, or browser compatibility gaps.

Use waterfall traces and Core Web Vitals to pinpoint where latency accumulates before customers abandon sessions.

Feed back into product

Share client uptime dashboards with product teams so they own regressions. Make ownership clear per route so fixes do not stall.

Use telemetry to prioritize front-end resilience fixes and caching. Address the worst offenders: long JavaScript tasks, unhandled promise rejections, and third-party SDK failures.

Publish status updates that mention client-side impact when only certain browsers or ISPs are affected.

Act quickly on regressions

Enable feature flags for risky front-end changes so you can roll back without redeploying. Pair them with RUM alerts that prove the rollback worked.

During incidents, show client and server metrics side by side in the war room so you don't chase the wrong layer.

Article stats

  • Author: Alex Kim
  • Role: Head of Reliability
  • Published: December 23, 2025
  • Reading time: 7 min

Tags

#rum#telemetry#uptime#watchdog

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