What live-data alerts are
Live-data alerts notify you when the performance of your website exceeds a threshold for real visitors. Unlike scan alerts, they are not based on individual lab scans but on the p75 value of real user measurements.
Auto mode
Auto mode automatically monitors all five metrics (LCP, CLS, INP, FCP, TTFB) using the Google recommendations as thresholds:
| Metric | Warning | Critical |
|---|---|---|
| LCP | > 2,500 ms | > 4,000 ms |
| CLS | > 0.1 | > 0.25 |
| INP | > 200 ms | > 500 ms |
| FCP | > 1,800 ms | > 3,000 ms |
| TTFB | > 800 ms | > 1,800 ms |
Advantages:
- no manual configuration needed
- all metrics monitored at once
- thresholds match Google's own assessment
A separate alert is triggered per metric. So you find out precisely which metric is the problem.
Custom mode
You choose a single metric and set the threshold yourself. This makes sense if you need stricter or more relaxed values than the Google defaults.
Configurable:
- Metric: LCP, CLS, INP, FCP or TTFB
- Threshold: the p75 value at which the alert should trigger
- Evaluation window: 30, 60 or 120 minutes — the period over which the p75 is calculated
- Minimum measurements: minimum number of measurements in the window (default: 20). Below this number the alert is ignored so that it does not fire when the data is too thin.
- Checks before alert: how many consecutive 5-minute checks have to exceed the threshold before an alert is triggered (1–3, default: 2). Prevents alerts caused by short-lived outliers.
Notifications
For each alert rule you can enable separately:
- Email — to the recipients stored under Profile > Notifications
- Webhook — to the configured webhook URL (events
rum.alert.triggeredandrum.alert.resolved)
Status of an alert rule
| Status | Meaning |
|---|---|
| Active | Rule is configured, no threshold exceeded |
| Watching | Threshold exceeded, but the consecutive threshold not yet reached |
| Triggered | Alert was triggered, notification sent |
| Resolved | Problem has cleared, recovery notification sent |
Recovery
When the p75 value falls back below the threshold, the alert is resolved automatically. You get a recovery notification (email and/or webhook) so that you know the problem has cleared.
After resolution the rule can trigger again if the values rise once more — as a new problem cycle.
Tips
- Auto mode is enough for most websites. Custom rules are only worthwhile if you need stricter or more relaxed values.
- A consecutive threshold of 2 is a good default. At 1 you get faster alerts, but also more false alarms on short-lived spikes.
- Do not set the minimum measurements too low — with fewer than 20 measurements in the window the p75 is not statistically reliable.